Polymerization monitoring and control using improved leading indicators

ABSTRACT

Embodiments of our invention relate generally to methods of monitoring and controlling polymerization reactions including reactions producing multimodal polymer products using multiple catalysts in a single reactor. Embodiments of the invention provide methods of rapidly monitoring and controlling polymerization reactions without the need to sample and test the polymer properties. The method uses reactor control data and material inventory data in a mathematical leading indicator function to control the reactor conditions, and thereby the products produced under those conditions.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional Applications60/512,502 and 60/512,355, both filed Oct. 17, 2003 and are hereinincorporated by reference.

TECHNICAL FIELD

Embodiments of the present invention provide methods of rapidlymonitoring and controlling polymerization reactions. The methods usemathematical functions derived from the reactor process data, themathematical functions being described as “Leading Indicators” (LI).

BACKGROUND

Attempts at controlling dynamic, continuous processes, includingpolyolefin production processes have been a long standing goal of theprocess industry.

Gas phase processes for the homopolymerization and copolymerization ofmonomers, especially olefin monomers, are well known in the art. Suchprocesses can be conducted, for example, by introducing the gaseousmonomer or monomers into a stirred and/or fluidized bed of resinparticles and catalyst.

In the fluidized-bed polymerization of olefins, the polymerization isconducted in a fluidized-bed reactor, wherein a bed of polymer particlesis maintained in a fluidized state by means of an ascending gas streamincluding gaseous reaction monomer. The polymerization of olefins in astirred-bed reactor differs from polymerization in a gas fluidized-bedreactor by the action of a mechanical stirrer within the reaction zone,which contributes to fluidization of the bed. As used herein, the term“fluidized-bed” also includes stirred-bed processes and reactors.

The start-up of a fluidized bed reactor generally uses a bed ofpreformed polymer particles. During the course of polymerization, freshpolymer is generated by the catalytic polymerization of the monomer, andpolymer product is withdrawn to maintain the bed at constant volume. Anindustrially favored process employs a fluidization grid to distributethe fluidizing gas to the bed, and also to act as a support for the bedwhen the supply of gas is cut off. The polymer produced is generallywithdrawn from the reactor via one or more discharge conduits disposedin the lower portion of the reactor, near the fluidization grid. Thefluidized bed includes a bed of growing polymer particles, polymerproduct particles and catalyst particles. This reaction mixture ismaintained in a fluidized condition by the continuous upward flow fromthe base of the reactor of a fluidizing gas which includes recycle gasdrawn from the top of the reactor, together with added make-up monomer.The fluidizing gas enters the bottom of the reactor and is passedthrough a fluidization grid, upwardly through the fluidized bed.

A variety of gas phase polymerization processes are known. For example,the recycle stream can be cooled to a temperature below the dew point,resulting in condensing a portion of the recycle stream, as described inU.S. Pat. Nos. 4,543,399 and 4,588,790. This intentional introduction ofa liquid into a recycle stream or reactor during the process is referredto generally as a “condensed mode” operation.

Further details of fluidized bed reactors and their operation aredisclosed in, for example, U.S. Pat. Nos. 4,243,619, 4,543,399,5,352,749, 5,436,304, 5,405,922, 5,462,999, and 6,218,484, thedisclosures of which are incorporated herein by reference.

For example, U.S. Pat. No. 5,525,678 suggests a catalyst including azirconium metallocene that produces a relatively low molecular weight,high comonomer-content polymer, and a titanium non-metallocene thatproduces a relatively high molecular weight, low comonomer-contentpolymer. Typically, ethylene is the primary monomer, and small amountsof hexene or other alpha-olefins are added to lower the density of thepolyethylene. The zirconium catalyst incorporates most of the comonomerand hydrogen, so that, in a typical example, about 85% of the hexene and92% of the hydrogen are in the low molecular weight polymer. Water isadded to control the overall molecular weight by controlling theactivity of the zirconium catalyst.

When polymerizing with two or more catalysts, it is desirable to monitorand control the relative contribution of each catalyst to the polymerproduct, so that the polymerization conditions can be adjusted to obtainthe desired polymer properties. The properties of the polymer producedin the reactor are affected by a variety of operating parameters, suchas reaction temperature, monomer feed rates, catalyst feed rates,co-catalyst feed rates, hydrogen gas concentration, or water feed rate.In order to produce polymer having a desired set of properties, polymerexiting the reactor is sampled and laboratory measurements carried outto characterize the polymer. If it is discovered that one or morepolymer properties are outside a desired range, polymerizationconditions can be adjusted, and the polymer resampled. This periodicsampling, testing and adjusting, however, is undesirably slow, sincesampling and laboratory testing of polymer properties is time-consuming.As a result, conventional processes can produce large quantities of“off-specification” polymer before manual testing and reactor controlcan effectively adjust the polymerization conditions.

In WO 03/044061 a rolling average of a ratio of two gas phase componentconcentrations, each concentration in turn expressed as a component'sgas phase mole fraction divided by its feed rate into the reactor, asseen in equation (7) on page 13 of that publication, is referred to as aLI. The LI gives an indication of the polymer properties being produced,without waiting for manual product analysis. This technique results inimproved control compared to the prior art. However, using the techniqueof WO 03/044061 yields somewhat inaccurate control when feed ratioschange and also the equation did not consider methods to choose theleading indicator target. Further, improvements made in industrial useapplied a leading indicator based on a weighting factor in turn based onpolymer residence time in the reactor. While using this latter method,the leading indicator based on polymer residence time, gave a betterindication of reactor behavior than the rolling average of WO 03/044061,a quicker, more responsive leading indicator was sought. Such a moreresponsive leading indicator might allow improved, more timely controlof polymerization processes, and in so doing, permit reduction ofoff-test or off-specification polymer in response to either unintendedreactor variable perturbations, or minimizing such off-test oroff-specification polymer in response to an intended change in reactorvariables, such as when changing such variables to achieve a differentclass of material by effecting a change to polymer properties such asmelt index, flow index, density, molecular weight, molecular weightdistribution or combinations thereof by adjusting reactor variables.

Thus, it would be desirable to have faster methods and more accuratemethods for monitoring and/or predicting changes in polymer properties,or changes in relative activities of catalysts, especially in multiplecatalyst processes. In addition, it would be desirable to have methodsto predict what reactor conditions would be required, based on simplereactor data and product properties, to produce a particular type orkind of polymer product. It is especially important to minimize theproduction of polymer product that does not meet desired specificationsduring times when the reactor process conditions are changing (eitherdeliberately or through process parameter drift).

SUMMARY

Among the embodiments of our invention are a method of olefinpolymerization, the method comprising: (a) determining a flow ratio to apolymerization reactor, FR₁, of a comonomer or hydrogen flow rate to amonomer flow rate provided to the reactor; determining the concentrationratio, GR₁, of the concentration of the selected comonomer or hydrogenconcentration to the monomer concentration in a recycle gas stream ofthe reactor, (b) obtaining a leading indicator function, LI, defined by:$\begin{matrix}{{LI} = {\frac{{FR}_{1}}{{GR}_{1}} = \frac{{(\beta)\left( {FR}_{2} \right)} + {\left( {1 - \beta} \right)\left( {FR}_{3} \right)}}{{GR}_{1}}}} & \left( {1a} \right)\end{matrix}$where GR₁ is the present value of either of the comonomer/ethyleneconcentration ratio or the present value of the hydrogen/ethyleneconcentration ratio at time T in the reactor, as determined by analysisof the recycle gas stream; where FR₁ is the present value of the flowratio into the reactor of either of the comonomer/ethylene ratio or thepresent value of the hydrogen/ethylene ratio, expressed as anexponentially weighted moving average (EWMA) at time T; where FR₂ is theinstantaneous flow ratio td minutes prior to time T; where FR₃ is anEWMA using the comonomer or hydrogen residence time td minutes prior totime T−1; where β=1−exp(−T/(comonomer residence time)=1−exp(Δt/τ); whereΔt=the time step chosen to update the LI calculation; where τ=theresidence time in the reactor of the comonomer or hydrogen that is usedto calculate the LI with the proviso that the comonomer dissolved in thepolymerized olefin is included in said comonomer used to calculate theLI; (c) comparing the LI to a target value; and (d)

adjusting at least one reactor parameter in response to a deviationbetween the LI and the target value.

In another embodiment a method to achieve control of a leading indicatorin a gas phase polymerization reaction in a polymerization reactor, iscontemplated comprising: a) calculating a leading indicator, (LI), suchthat the numerator and denominator have the same dynamic response toprocess changes; b) choosing at least one process sensitive variable tomanipulate to control said leading indicator (LI); c) manipulating theprocess sensitive variable; and d) removing a polymer product.

In another embodiment a process for polymerizing olefins in a gas-phasefluidized bed polymerization reactor is contemplated, the processcomprising: (a) determining a flow ratio into the polymerizationreactor, FR₁, of a comonomer or hydrogen flow rate to a monomer flowrate provided to the reactor; determining the concentration ratio, GR₁,of the selected comonomer or hydrogen concentration to the monomerconcentration in a recycle gas stream of the reactor, (b) obtaining aleading indicator function, LI, defined by: $\begin{matrix}{{LI} = {\frac{{FR}_{1}}{{GR}_{1}} = \frac{{(\beta)\left( {FR}_{2} \right)} + {\left( {1 - \beta} \right)\left( {FR}_{3} \right)}}{{GR}_{1}}}} & \left( {1a} \right)\end{matrix}$where GR₁ is the present value of either of the comonomer/ethyleneconcentration ratio or the present value of the hydrogen/ethyleneconcentration ratio at time T in the reactor, as determined by analysisof the recycle gas stream; where FR₁ is the present value of the flowratio into the reactor of either of the comonomer/ethylene ratio or thepresent value of the hydrogen/ethylene ratio, expressed as anexponentially weighted moving average (EWMA) at time T; where FR₂ is theinstantaneous flow ratio td minutes prior to time T; where FR₃ is anEWMA using the comonomer or hydrogen residence time td minutes prior totime T−1; where β=1−exp(−T/(comonomer residence time)=1−exp(Δt/τ); whereΔt=the time step chosen to update the LI calculation; where τ=theresidence time in the reactor of the one of comonomer or hydrogen thatis used to calculate the LI, with the proviso that the comonomerdissolved in a polymer made in the olefin polymerization, is included insaid comonomer used to calculate the LI; (c) comparing the LI to atarget value; and (d) adjusting at least one reactor parameter inresponse to a deviation between the LI and the target value; whereinsaid polymerization comprises said ethylene, said comonomer selectedfrom 1-butene, 1-hexene or combinations thereof, and hydrogen; whereinthe olefin polymerization is catalyzed by a supported bimetalliccatalyst system comprising at least one metallocene catalyst and atleast one non-metallocene transition metal catalyst, and wherein saidpolymer product comprises a molecular weight distribution, a compositiondistribution, or both a molecular weight distribution and a compositiondistribution, that are broad or bimodal, or both broad and bimodal;wherein the at least one metallocene catalyst compound is (RCp)₂MX₂,wherein Cp is a substituted cyclopentadienyl ring, M is zirconium; R isa n-butyl, and X is fluoride; wherein the at least one reactor parameteris selected from the group consisting of monomer feed rate, comonomerfeed rates, catalyst feed rates, cocatalyst feed rates, hydrogen feedrate, reactor temperature, monomer partial pressure, comonomer partialpressure, hydrogen partial pressure, water feed rate, carbon dioxidefeed rate, impurity feedrate, condensing agent feedrate, isopropylalcohol feedrate, oxygen feedrate, and combinations thereof.

The novel features which are believed to be characteristic of theinvention, both as to its organization and method of operation, togetherwith further objects and advantages will be better understood from thefollowing description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference isnow made to the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates a fluidized bed reactor generally useful in thepractice the embodiments of the present invention.

FIG. 2 shows the response of the leading indicators of embodiments ofour invention as a function of time, compared to other, comparativeleading indicator functions. The figure shows the correct-phasecomparison between a leading indicator of embodiments of our inventionand the change in FI of a resin (polyolefin) being produced using thecatalyst system disclosed below.

FIG. 3 illustrates the change in target leading indicator LI_(T) and amethod to efficiently determine the best LI_(T) in case of changes inreactor parameters.

FIG. 4 shows the impact of FI_(H) changes on the LI.

DESCRIPTION

In one embodiment of our invention we describe a method of polymerizingolefins. Using analysis of reaction component concentrations in areactor and reaction component feed rates to a reactor we have appliedmathematical analysis and manipulation to derive a highly accurate andvery predictive leading indicator. These leading indicators provide forrapid diagnosis of reactor variable perturbations and the impact suchperturbations have on the polymer produced, permitting rapid recoveryfrom unplanned variable changes. Additionally, such leading indicatorspermit operators to make deliberate changes in polymer characteristics(based on purposely changing one or more reactor variables) and to makesuch deliberate changes with a shorter, more economical transition timefrom one set of characteristics to another.

The methods of embodiments of our invention are applicable to severalreactor types, for example, solution reactors, slurry loop reactors,supercritical loop reactors, or fluidized-bed, gas-phase reactors. Whilethe discussion herein uses fluidized-bed, gas-phase reactors as anexample, it should be understood that the methods are applicable to theother reactor types.

Leading Indicators

As used herein, the term “leading indicator” is used to mean a functionof a ratio of at least two component concentrations, each concentrationin turn may be expressed as a component's mole fraction divided by itsfeed rate (in suitable units known in the art such as mass per unittime, or corrected volume per unit time) into the reactor. Thus, aleading indicator (“LI”) can be expressed as the mole fraction χ_(i),the mole fraction of the i'th component based on the total moles ofcomponents, or based on a subset of the components. Alternatively, aleading indicator can be based on a mathematically rearranged formulabased on the ratio of reactor component feeds and the reactorconcentrations; the latter measured at a suitable location in thereactor. While in the present document we discuss gas phaseconcentrations or component feed rates into a reactor, these terms applyequally to solution or slurry reactors, where the concentrations andflow rates will refer to liquid or slurry concentrations or feed rates.Any discussion of gas ratio in a reactor or gas flow rates or ratioswill be understood to mean alternately a component concentration and acomponent feed rate, where the reactants are liquids or slurries asusually employed in the reaction mechanisms discussed herein.

In one aspect of the present invention we provide a method ofpolymerizing olefins in a gas-phase fluidized bed reactor utilizingleading indicators. For example, concentrations or gas ratios, GR, oftwo reaction components, for instance, the primary monomer, such asethylene or propylene, and comonomer (such as butene-1, hexene-1 and/oroctene-1) or hydrogen, are determined in the recycle gas stream of thereactor. Analysis of the gas ratio (GR) is determinative of the gasratio inside the reactor at a specific time. The gas ratio or ratios(GR) are compared to the flow ratios (FR) of the reaction componentsinto the reactor. These ratios (FR and GR) are incorporated withexponential weighting factors (or filter constants) to provide leadingindicator functions, LI, which are useful to control an ongoingpolymerization reaction or to change reaction conditions in a reactor toproduce different polymers or in other words to alter polymer physicalproperties, or useful to control polymers produced by multiple catalystsystems where the multiple catalysts may be the same or different andthe catalyst systems producing polymers that may have multimodalmolecular weight distributions and/or comonomer contents. In thisembodiment, the Leading Indicator measurement is concerned with thecurrent, actual state of a reactor and the calculation/equation shownbelow uses reactor variables to determine the current Leading Indicator.Control of the leading indicator function may be achieved by manual,automatic, or a combination of manual and automatic adjustments ofreactor conditions

Because analysis of the recycle gas stream to determine gas ratio orratios (GR), takes a finite time (td or delay time) and it also takes afinite time for the gas ratio or ratios (GR) to change in response to aflow ratio (FR) change, a manipulation (dynamic compensation) must beperformed on the numerator to keep the numerator and denominator inphase and the leading indicator (LI) accurate. Whichever ratio is usedin the denominator will also be used in the numerator, that is, ifethylene to comonomer is the ratio in the denominator, the ethylene tocomonomer ratio will also be the basis for the numerator. Or, ifethylene to hydrogen is the ratio in the denominator, the ethylene tohydrogen ratio will also be the basis for the numerator. In one aspectof the invention, a leading indicator (LI) is calculated according tothe following general equation/calculation (1a). Note, for convenienceand consistency, the notation for the various components of thecalculation is different than earlier presented in ProvisionalApplications 60/512,502 and 60/512,355. Both versions are shown belowwith cross reference to the previous version of the calculation/equation(here (1)): $\begin{matrix}{{LI} = {\frac{{FR}_{{avg},T}}{{GR}_{{inst}.T}} = \frac{\left( {{WF}_{pref} \times {FR}_{{{inst}.T} - {td}}} \right) + {\left( {1 - {WF}_{pref}} \right) \times {FR}_{{avg},{{({T - {td}})} - 1}}}}{{GR}_{{inst}.T}}}} & (1) \\{{LI} = {\frac{{FR}_{1}}{{GR}_{1}} = \frac{{(\beta)\left( {FR}_{2} \right)} + {\left( {1 - \beta} \right)\left( {FR}_{3} \right)}}{{GR}_{1}}}} & \left( {1a} \right)\end{matrix}$

Where GR₁=GR_(inst.T)=present value of either of the comonomer/ethylenegas ratio or the present value of the hydrogen/ethylene gas ratio attime T(now) in the reactor, as determined by analysis of the recyclestream.

Where FR₁=FR_(avg, T)=the present value of the flow ratio of either ofthe comonomer/ethylene ratio or the present value of thehydrogen/ethylene ratio expressed as an exponentially weighted movingaverage (EWMA) at time T.

Where FR₂ FR_(inst. T-td)=the instantaneous Flow Ratio td minutes priorto time step T.

Where FR₃=FR_(avg., (T-td)-1)=a EWMA using the comonomer or hydrogenresidence time td minutes prior to time step T−1.

β=WF_(pref.)=1−exp(−T/(comonomer residence time)=an exponentialweighting factor or filter constant (based on comonomer or hydrogenresidence time in the reactor)=1−exp(−Δt/τ), where Δt=the time stepchosen to update the LI calculation (typically=1 minute), τ=theresidence time of the raw material (typically either comonomer orhydrogen) that is used to calculate the LI. This residence time iscalculated by adding the weight of raw material (i.e. monomer, andcomonomer) in the recycle gas stream plus the estimated amount of rawmaterial dissolved in the polymer bed, with the sum being divided by theraw material feedrate.

The value of a leading indicator (LI) or a function of a leadingindicator (LI), such as a rescaled value or a reciprocal, is compared toa target value, and at least one reactor parameter is adjusted inresponse to a deviation between a leading indicator (LI) or the functionof a leading indicator (LI) and the target value. Monitoring of thisleading indicator permits improved rapid adjustments of reactorparameters to control the properties of polymers that are produced,rapid diagnosis of reactor problems, and the subsequent rapid resolutionof reactor problems, compared to using the laboratory analysis ofpolymer samples alone.

In another embodiment of the invention, a leading indicator (LI) ismonitored as a function of time, and the time behavior of a leadingindicator (LI) is monitored and compared to a target function.

In another embodiment of our invention, a method of calculating aleading indicator target value (LI_(T)) to control a gas phasepolymerization reactor and thereby control the properties of a polymerproduct produced therein is provided by obtaining a leading indicator(LI) data based on present and past reactor operating parameters, andpast analysis of a polymer product produced in the reactor under pastleading indicator parameters, and then calculating a new, target leadingindicator (LI_(T)) that relates to a desired future polymer product (thefuture desired polymer product will generally have at least one physicalproperty changed or altered compared to the polymer produced at thepresent time) wherein the target leading indicator (LI_(T)) is definedas in the following Equations 2a & 3a. Note, for convenience andconsistency, the notation of the various components of the calculationis different than earlier presented in Provisional Application60/512,502 and 60/512,355. Both are shown below with cross reference tothe previous version of the calculation/equation (here (2 & 3)): Thisequation is based on the discovery that the target leading indicator(LI_(T)) to produce a target flow index (FI_(T)) (where Flow Indexthroughout this document is I_(21.6), as determined by ASTM D1238-01Procedure B at condition 190/21.6) is a function of the flow index ofthe higher molecular weight polymer produced by the catalyst systemunder current reactor parameters (FI_(H)). For example, if the flowindex of the higher molecular weight polymer (FI_(H)) increases, thenthe target leading indicator (LI_(T)) decreases. Or, stated another way,the breadth of the molecular weight distribution affects the relativeamount of each component that must be made to achieve the target FI:LI _(target)=(ln(FI _(target))−A ₁ −C _(CAT1) ×FI _(HMW,Current))/C_(CAT2.);  (2)LI _(T)=(ln(FI _(T))−A ₁ −C′ ₂ ×FI _(H))/C′ ₂  (2a)where A ₁=ln(FI _(OLD))−C _(CAT2) ×LI _(PREVIOUS-SBA) −C _(CAT1) ×FI_(HMW,old)  (3)where A ₁=ln(FI _(O))−C′ ₂ ×LI _(P) −C′ ₁ ×FI _(HO)  (3a)where FI_(target)=FI_(T) is the target flow index of a polymer productthat is desired after adjustment of reaction conditions to a new targetleading indicator (LI_(T)). FI_(OLD)=FI_(O) is the measured flow indexof polymer produced according to the previous leading indicator reactorconditions; C_(CAT1)=C′₁ is a constant related to the catalyst system;LI_(PREVIOUS-SBA)=LI_(P) is the leading indicator calculated, by asingle back average technique (SBA), from the previous time period forthe time that the measured flow index of polymer produced according tothe previous leading indicator reactor conditions (FI_(O)) and FI_(HO)measurements were performed; and FI_(HMW,old)=FI_(HO) is the flow indexof the higher molecular weight polymer measured on polymer producedaccording to the previous leading indicator conditions.FI_(HMW,Current)=FI_(H) is the flow index of the higher molecular weightpolymer produced by the catalyst system under current reactorparameters. Note that the determination of FI_(H) is useful in a bi ormultimodal molecular weight distribution polymer, i.e. where two or morecatalysts are used to produce a polymer having at least one populationof molecular weight distributions that are relatively low and at leastone distribution that is relatively high. In an alternate embodiment,the flow index of a polymer having low and high (relative) molecularweights can also use the flow index of the lower molecular weightpolymer (FI_(L)) for this calculation (2a & 3a). C_(CAT2)=C′₂ is aconstant related to the catalyst system. C′₂ and C′₂ are determined foreach catalyst system or polymer composition by comparing at least twodata points with known leading indicator values (LI) and flow indexvalues (FI) and at least two different flow indexes of the highermolecular weight polymer produced by the catalyst system under currentreactor parameters (FI_(H)) and solving algebraically for C′₁ and C′₂.C′₁ and C′₂ can vary respectively from 1-10 and 0.1-10, and all elementsof these ranges. Likewise, more complicated determinations (generallynon-linear) of leading indicators are also contemplated, for instanceC_(x), the x^(th) reactor constant, could be used in conjunction withthe square of (FI_(H)) (or in an alternate embodiment using (FI_(L))).

In another embodiment, which will be most useful when FI_(O) is nearFI_(T) and a change in FI_(H) is planned, a method of calculating aleading indicator target (LI_(T)) value to control a polymerizationreactor and thereby to control the properties of a polymer productproduced therein is contemplated, comprising: a) calculating a leadingindicator target (LI_(T)) wherein said leading indicator target (LI_(T))is determined by:LI _(T) =LI _(P) +C′ ₄ +C′ ₃×(FI _(H) −FI _(HO));where C′₃ and C′₄ are constants related to the catalyst system; whereLI_(P) is the leading indicator calculated from the previous time periodfor the time that the samples upon which FI_(HO) was measured, whereFI_(HO) is a flow index of a higher molecular weight portion of saidpolymer measured on polymer produced according to the previous leadingindicator conditions, determined by:FI _(HO)=ln(−0.33759+0.516577*ln(I _(21.6))−0.01523*(I _(21.6) /I_(2.16)));where FI_(H) is a flow index of the higher molecular weight portion ofpolymer produced by the catalyst system under current reactorparameters, estimated from models showing changes in FI_(H) based onchanges in reaction conditions; and b) changing at least one reactorparameter to adjust the leading indicator toward the new target. C′₃ andC′₄ may be calculated using data from the relevant catalyst systemcomparing leading indicators for at least 2 data points where FI_(H)changes and FI is the same. C′₃ may be −0.7, or range from −6.0 to +4.0,or from −0.4 to −1.0, C′₄ may be 0, or range from −3.0 to +3.0, or from−0.3 to +0.3.

At least one reactor parameter is adjusted to change the leadingindicator toward the new target leading indicator (LI_(T)).

The FI_(H) model will depend on the exact catalyst system and molecularweight targets. The FI_(H) model used for the catalyst system in theexamples of this patent is:FI _(H) =FIH _(O)+0.005×(COCAT−COCAT _(O))+0.072×(C2PP−C2PP_(O))+35.3×(H2/C2−H2/C2_(O))

Where COCAT and COCAT_(O) are current and previous, respectively, movingaverages of the co-catalyst to ethylene feed ratio in units of parts permillion by weight; C2PP and C2PP_(O) are current and previous,respectively, moving averages of the ethylene partial pressure in bar;and H2/C2 and H2/C2_(O) are current and previous, respectively, movingaverages of the hydrogen to ethylene molar ratio in the cycle gas,dimensionless.

LI_(PREVIOUS-SBA)=LI_(P) is an exponentially weighted moving average ofthe LI, calculated with a weighting factor, λ=1−exp(−Δt/(polymerresidence time) based on the polymer residence time in the reactor.

This calculation is:LI _(P)=(λ×LI)+(1−λ)×LI _(T-1)

In another aspect of the invention, at least two leading indicators aremonitored and compared with target values or target functions. Forexample, a LI based on hydrogen and ethylene may be used in combinationwith a LI based on hexene and ethylene.

In aspects described herein, suitable reactor components to calculate aLI include, for example, hydrogen, monomers, comonomers, or any tracercomponent that is preferentially incorporated into one portion of thepolymer composition distribution. Suitable reactor parameters to controlLI include, for example, monomer feed rate, comonomer feed rates,catalyst feed rates, cocatalyst feed rates, hydrogen feed rate, reactortemperature, monomer partial pressure, comonomer partial pressure,hydrogen partial pressure, water feed rate, carbon dioxide feed rate,impurity feedrate, condensing agent feedrate, isopropyl alcoholfeedrate, oxygen feedrate, and combinations thereof.

In another aspect of the invention, a method of achieving control of aleading indicator LI is provided and generally comprises choosing atleast one process sensitive parameter for manipulating to control aleading indicator function LI, and, manipulating the process sensitiveparameter using changes in the values of that process sensitiveparameter to control a leading indicator (LI).

In another embodiment of the invention, a filter is applied to provide atrue, noise-free leading indicator LI for stable automatic controlbefore performing the changes in the values of that process parameter.The filtering technique is described in “Introduction to Control Theorywith Applications to Process Control” [Lowell B. Koppel, Prentice-Hall,1968, Appendix E.]

In another aspect of the invention, the polymerization is catalyzed by acatalyst system including a first catalyst producing a first polymer anda second catalyst producing a second polymer, and the method produces apolymer product having a distribution of molecular weight, composition,or both molecular weight and composition, that is broad or bimodal orboth broad or bimodal. Throughout this description, bimodal means atleast two molecular weight and/or composition distributions, which mayalso include “multi-modal” which means three, four, five, six, seven ormore molecular weight and/or composition distributions. The reactorparameter can be chosen to selectively alter the relative activity ofthe first and second catalysts or the relative feedrates of the twocatalysts, provide control over the bimodal distribution ordistributions, or both.

In another embodiment of the invention the polymerization is carried outusing supported bimetallic catalysts where at least one catalyst is aZiegler-Natta based catalyst.

In another embodiment of the invention the polymerization is carried outusing supported bimetallic catalysts where at least one catalyst is ametallocene based catalyst.

In another aspect of the invention, the polymerization is carried outusing supported bimetallic catalysts where at least one catalyst is atleast one metallocene catalyst-based compound and/or at least one othermetal containing catalyst such as a “Ziegler-Natta” type catalyst aswould be known in the art.

In another aspect of the invention the polymerization is carried outusing supported bimetallic catalysts where one component of the catalystis a metallocene compound, Cp₂MX₂, wherein Cp is a substitutedcyclopentadienyl ring, M is a Group 4 metal, and X is a halide. Inanother embodiment wherein the at least one metallocene catalystcompound is (RCp)₂MX₂, wherein Cp is a substituted cyclopentadienylring, M is zirconium; R is an n-butyl, and X is fluoride.

The feed rates in Equation (1a) can be in any convenient units, as theunits will cancel. Mole fractions are dimensionless, and thus theleading indicator is also dimensionless. It should be appreciated thatuse of leading indicators as described herein is based on relative, notabsolute quantities. One or more leading indicators is monitored as afunction of time, and changes in the one or more leading indicator(s)are used as described below to monitor and/or control the reaction.Thus, functions of Equation (1a) or variations thereof are also withinthe scope of embodiments of the invention. For example, the reciprocalof a leading indicator is still a leading indicator, and other functionscan be applied to the numerator, denominator or the ratios or averagesas desired or required depending on the monomers being polymerized andthe conditions of the reaction, provided that the function thus obtainedpermits monitoring and/or controlling the reactor changes over a periodof time.

The numerator in Equation (1a) can relate to any quantity to which oneor both of the catalyst components is sensitive, such as, for examplehydrogen gas concentration or the gas-phase concentration of acomonomer. The terms “numerator” and “denominator” are used only forconvenience, as the reciprocal of a leading indicator is itself aleading indicator.

In one embodiment, the leading indicator is based on the relativeamounts of hydrogen gas (H₂) and ethylene monomer, the ethylene monomerbeing denoted “C₂” for convenience. In this embodiment, the leadingindicator is referred to as the “H₂ leading indicator”.

In another embodiment, the leading indicator is based on the relativeamounts of a comonomer (CM) and the major monomer (M), i.e., the methodproduces copolymers having a majority of polymerized monomer units and aminority of polymerized comonomer units.

In another embodiment, the leading indicator is based on ethylene as the(major) monomer and the comonomer is selected from the group consistingof C₃-C₁₂ alpha-olefins, hydrogen and mixtures thereof.

In another embodiment, the leading indicator is based on ethylene as the(major) monomer and the comonomer is selected from the group consistingof C₃-C₈ alpha-olefins, hydrogen and mixtures thereof.

In another embodiment, the leading indicator is based on ethylene as the(major) monomer and the comonomer is selected from the group consistingof C₃-C₆ alpha-olefins, hydrogen and mixtures thereof.

In another embodiment, the olefin polymerization is catalyzed by acatalyst system comprising a first catalyst producing a first polymerand a second catalyst producing a second polymer, and wherein the methodproduces a polymer product having a distribution of molecular weight andcomposition that is broad and bimodal.

In another embodiment, the step of adjusting at least one reactorparameter is effective to alter the relative productivity of the firstand/or second catalysts.

In another embodiment, the catalyst system comprises at least onemetallocene catalyst and at least one non-metallocene catalyst and/orthe at least one metallocene and at least one non-metallocene catalystsmay be supported and both may be present on the same support or each maybe on a separate support.

In another embodiment, the olefin polymerization is catalyzed by asupported bimetallic catalyst system comprising at least one metallocenecatalyst and at least one non-metallocene transition metal catalyst, andwherein the method produces a polymer product having a distribution ofmolecular weight, composition, or both molecular weight and composition,that is broad and/or bimodal. For example, in a copolymer of ethylenemonomer and comonomer (1-butene, 1-hexene 1-octene or combinationsthereof), the leading indicator is based on the relative amounts of1-butene, 1-hexene, 1-octene or combinations thereof as comonomer(s) andethylene.

In another embodiment, the polymer is a copolymer of ethylene and1-hexene, or ethylene and 1-butene and the leading indicator is based onthe relative amounts of 1-hexene (or 1-butene) comonomer(s) andethylene.

Flow rates of various components can be measured using conventional flowmeters or Coriolis Flow Meters. The gas phase concentration ofcomponents can be determined by analysis of the recycle gas stream withgas analyzer 38 (FIG. 1).

If desired, one or more leading indicators can be determined as afunction of time.

In another embodiment, LI is monitored as a function of time, and thetime behavior of LI is monitored and compared to a target function. Theleading indicator can be determined at a plurality of times. The timeinterval between determinations of LI can be any convenient interval. Itis convenient to determine LI at regular intervals, such as everyminute, every 5 minutes, or other larger or smaller time interval,although the time intervals can also be random.

In another embodiment, at least two leading indicators are monitored andcompared with target values or target functions. In an embodiment, theH₂ leading indicator and a comonomer leading indicator (e.g. based on1-octene, 1-hexene or 1-butene as comonomer) are used.

Fluidized-Bed Reactor

Fluidized-bed reactors are well-known in the art; an example of afluidized bed reactor is described herein, for illustrative purposesonly. Those skilled in the art will recognize that the numerousmodifications and enhancements can be made, as desired, to thefluidized-bed reactor.

The catalyst used is not particularly limited, and can include, forexample, one or more Ziegler-Natta catalysts and/or metallocenecatalysts. Mixtures of catalysts can also be used. In particular,polymerization can be carried out with two or more different catalystspresent and actively polymerizing at the same time, in a single reactor.The two or more catalysts can be of different catalyst types, such as anon-metallocene catalyst and a metallocene catalyst, to produce aproduct resin having desirable properties. The catalysts can be fed tothe reactor separately or as a physical mixture, or each catalystparticle can contain more than one catalyst compound. When the catalystinclude two active catalyst sites producing polymers of differentmolecular weight and/or different comonomer content, the polymer productcan have a bimodal distribution of molecular weight, comonomer, or both.Such bimodal products can have physical properties that are differentfrom those that can be obtained from either catalyst alone, or frompost-reactor mixing of the individual unimodal resins obtained from eachcatalyst alone.

FIG. 1 illustrates a gas-phase fluidized bed reactor 20 useful inperforming the method of the present invention. The reactor 20 has areactor body 22, which is generally an upright cylinder having afluidization grid 24 located in its lower regions. The reactor body 22encloses a fluidized bed zone 26 and a velocity reduction zone 28, whichis generally of increased diameter compared to the diameter of thefluidized bed zone 26 of the reactor body 22.

The gaseous reaction mixture leaving the top of the reactor body 22,termed the “recycle gas stream,” contains principally unreacted monomer,unreacted hydrogen gas, inert condensable gases such as isopentane, andinert non-condensable gases such as nitrogen. The recycle gas stream istransferred via line 30 to compressor 32, and from compressor 32 to heatexchanger 34. An optional cyclone separator 36 may be used as shown,upstream of compressor 32, to remove fines, if desired. A gas analyzer38 can be used to sample the recycle gas stream to determineconcentrations of various components. Typically, the gas analyzer is agas phase chromatograph (GPC), or a spectrograph such as a near-infraredspectrometer or a Fourier transform near-infrared spectrometer (FT-NIR).An additional heat exchanger (not shown) may also be used if desired,and may be located upstream of compressor 32.

The cooled recycle gas stream exits the heat exchanger 34 via line 40.As discussed above, the cooled recycle gas stream can be gaseous, or canbe a mixture of gaseous and liquid phases. FIG. 1 shows an optionalconfiguration wherein at least a portion of the recycle gas stream iscooled to a temperature at or below the temperature where liquidcondensate begins to form (the dew point). All or a portion of theresultant gas liquid mixture is transferred via line 40 to a separator42, where all or a portion of the liquid is removed. All or a portion ofthe gas stream, which may contain some liquid, is transferred via line44 to a point below the fluidization grid 24 in the lower region of thereactor. An amount of upwardly flowing as, sufficient to maintain thebed in a fluidized condition, is provided in this way.

Those skilled in the art will understand that less gas is required tomaintain fluidization when the reactor employed is a stirred bedreactor.

An optional compressor 46 may be provided to ensure that a sufficientvelocity is imparted to the gases flowing through line 44 into thebottom of the reactor. The gas stream entering the bottom of the reactormay contain condensed liquid, if desired.

All or a portion of the liquid phase separated from the recycle streamin separator 42 is transferred via line 48 to a manifold 50 located ator near the top of the reactor. If desired, a pump 52 may be provided inline 48 to facilitate the transfer of liquid to manifold 50. The liquidentering manifold 50 flows downward into manifold 54 through a pluralityof conduits 56 which have good heat exchange properties and which are inheat exchange contact with the wall of the reactor. The passage ofliquid through the conduits 56 cools the interior wall of the reactorand warms the liquid to a greater or lesser extent, depending upon thetemperature differential and the duration and extent of heat exchangecontact. Thus by the time the liquid entering manifold 50 reachesmanifold 54, it has become a heated fluid which may have remained in anentirely liquid state or it may have become partially or totallyvaporized.

As shown in FIG. 1, the heated fluid (gas and/or liquid) is passed frommanifold 54 via line 58 to combine with gases leaving the separator 42via line 44, prior to entry into the reactor in the region below thefluidization grid 24. In like manner, make-up monomer can be introducedinto the reactor in either liquid or gaseous form via line 60. Gasand/or liquid collected in manifold 54 may also be transferred directlyinto the reactor (not shown) in the region below the fluidization grid.

Product polymer particles can be removed from the reactor via line 62 inthe conventional way, as for example by the method and apparatusdescribed in U.S. Pat. No. 4,621,952.

Catalyst is continuously or intermittently injected into the reactorusing a catalyst feeder (not shown) such as the device disclosed in U.S.Pat. No. 3,779,712. The catalyst may be fed into the reactor at a point20 to 40 percent of the reactor diameter away from the reactor wall andat a height of about 5 to about 30 percent of the height of the bed.Suitable catalysts are described below.

A gas, which is inert to the catalyst, such as nitrogen or argon, may beused to carry catalyst into the bed. Cold condensed liquid from eitherseparator 42 or from manifold 54 may also be used to transport catalystinto the bed.

In methods of the present invention, the fluidized bed reactor isoperated to form polyolefins having a bimodal molecular weightdistribution, a bimodal comonomer distribution, or both. Suitablepolyolefins include, but are not limited to, polyethylene(s),polypropylene, polyisobutylene, and copolymers thereof.

In one embodiment, at least one polyolefin includes polyethylenecopolymers. Low density polyethylene (“LDPE”) can be prepared at highpressure using free radical initiators, or in gas phase processes usingZiegler-Natta or vanadium catalysts, and typically has a density in therange of 0.916-0.928 g/cm³. LDPE is also known as “branched” or“heterogeneously branched” polyethylene because of the relatively largenumber of long chain branches extending from the main polymer backbone.Polyethylene with the same density range, i.e., 0.916 to 0.928 g/cm³,which is linear and does not contain long chain branching is also known;this “linear low density polyethylene” (“LLDPE”) can be produced withconventional Ziegler-Natta catalysts or with metallocene catalysts.Relatively higher density LDPE, typically in the range of 0.928 to 0.940g/cm³, is sometimes referred to as medium density polyethylene (“MDPE”).Polyethylenes having still greater density are the high densitypolyethylenes (“HDPEs”), i.e., polyethylenes having densities greaterthan 0.940 g/cm³, and are generally prepared with Ziegler-Nattacatalysts. Very low density polyethylene (“VLDPE”) is also known. VLDPEscan be produced by a number of different processes yielding polymerswith different properties, but can be generally described aspolyethylenes having a density less than 0.916 g/cm³, typically 0.890 to0.915 g/cm³ or 0.900 to 0.915 g/cm³.

Polymers having more than two types of monomers, such as terpolymers,are also included within the term “copolymer” as used herein. Suitablecomonomers include α-olefins, such as C₃-C₂₀ α-olefins or C₃-C₁₂α-olefins. The α-olefin comonomer can be linear or branched, and two ormore comonomers can be used, if desired. Examples of suitable comonomersinclude linear C₃-C₁₂ α-olefins, and α-olefins, and α-olefins having oneor more C₁-C₃ alkyl branches, or an aryl group. Examples includepropylene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene;1-pentene with one or more methyl, ethyl or propyl substituents;1-hexene with one or more methyl, ethyl or propyl substituents;1-heptene with one or more methyl, ethyl or propyl substituents;1-octene with one or more methyl, ethyl or propyl substituents; 1-nonenewith one or more methyl, ethyl or propyl substituents; ethyl, methyl ordimethyl-substituted 1-decene; 1-dodecene; and styrene. It should beappreciated that the list of comonomers above is merely exemplary, andis not intended to be limiting. Comonomers include propylene, 1-butene,1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and styrene.

Other useful comonomers include polar vinyl, conjugated andnon-conjugated dienes, acetylene and aldehyde monomers, which can beincluded in minor amounts in terpolymer compositions. Non-conjugateddienes useful as co-monomers may be straight chain, hydrocarbondiolefins or cycloalkenyl-substituted alkenes, having 6 to 15 carbonatoms. Suitable non-conjugated dienes include, for example: (a) straightchain acyclic dienes, such as 1,4-hexadiene and 1,6-octadiene; (b)branched chain acyclic dienes, such as 5-methyl-1,4-hexadiene;3,7-dimethyl-1,6-octadiene; and 3,7-dimethyl-1,7octadiene; (c) singlering alicyclic dienes, such as 1,4-cyclohexadiene; 1,5-cyclooctadieneand 1,7-cyclododecadiene; (d) multi-ring alicyclic fused and bridgedring dienes, such as tetrahydroindene; norbornadiene;methyl-tetrahydroindene; dicyclopentadiene (DCPD);bicyclo-(2.2.1)-hepta-2,5-diene; alkenyl, alkylidene, cycloalkenyl andcycloalkylidene norbornenes, such as 5-methylene-2-norbornene (MNB),5-propenyl-2-norbornene, 5-isopropylidene-2-norbornene,5-(4-cyclopentenyl)-2-norbornene, 5-cyclohexylidene-2-norbornene, and5-vinyl-2-norbornene (VNB); and (e) cycloalkenyl-substituted alkenes,such as vinyl cyclohexene, allyl cyclohexene, vinyl cyclooctene, 4-vinylcyclohexene, allyl cyclodecene, and vinyl cyclododecene. Thenon-conjugated dienes that may be typically used are dicyclopentadiene,1,4-hexadiene, 5 -methylene-2-norbornene, 5-ethylidene-2-norbornene, andtetracyclo-(Δ-11,12)-5,8-dodecene.

Catalysts

General Definitions

As used herein, the phrase “catalyst system” includes at least one“catalyst component” and at least one “activator”, both of which aredescribed further herein. The catalyst system may also include othercomponents, such as supports, and is not limited to the catalystcomponent and/or activator alone or in combination. The catalyst systemmay include any number of catalyst components in any combination asdescribed herein, as well as any activator in any combination asdescribed herein.

As used herein, the phrase “catalyst compound” includes any compoundthat, once appropriately activated, is capable of catalyzing thepolymerization or oligomerization of olefins, the catalyst compoundcomprising at least one Group 3 to Group 12 atom, and optionally atleast one leaving group bound thereto.

As used herein, the phrase “leaving group” refers to one or morechemical moieties bound to the metal center of the catalyst componentthat can be abstracted from the catalyst component by an activator, thusproducing the species active towards olefin polymerization oroligomerization. The activator is described further below.

As used herein, in reference to Periodic Table “Groups” of Elements, the“new” numbering scheme for the Periodic Table Groups are used as in theCRC HANDBOOK OF CHEMISTRY AND PHYSICS (David R. Lide ed., CRC Press81^(st) ed. 2000).

As used herein, a “hydrocarbyl” includes aliphatic, cyclic, olefinic,acetylenic and aromatic radicals (i.e., hydrocarbon radicals) comprisinghydrogen and carbon that are deficient by one hydrogen. A“hydrocarbylene” is deficient by two hydrogens.

As used herein, an “alkyl” includes linear, branched and cyclic paraffinradicals that are deficient by one hydrogen. Thus, for example, a —CH₃group (“methyl”) and a CH₃CH₂— group (“ethyl”) are examples of alkyls.

As used herein, an “alkenyl” includes linear, branched and cyclic olefinradicals that are deficient by one hydrogen; alkynyl radicals includelinear, branched and cyclic acetylene radicals deficient by one hydrogenradical.

As used herein, “aryl” groups includes phenyl, naphthyl, pyridyl andother radicals whose molecules have the ring structure characteristic ofbenzene, naphthylene, phenanthrene, and anthracene. For example, a C₆H₅⁻ aromatic structure is an “phenyl”, a C₆H₄ ²⁻ aromatic structure is an“phenylene”. An “arylalkyl” group is an alkyl group having an aryl grouppendant therefrom, examples of which include benzyl, phenethyl,tolylmethyl; an “alkylaryl” is an aryl group having one or more alkylgroups pendant therefrom, examples of which include tolyl, xylyl,mesityl, and cumyl.

As used herein, an “alkylene” includes linear, branched and cyclichydrocarbon radicals deficient by two hydrogens. Thus, —CH₂—(“methylene”) and —CH₂CH₂— (“ethylene”) are examples of alkylene groups.Other groups deficient by two hydrogen radicals include “arylene” and“alkenylene”.

As used herein, the phrase “heteroatom” includes any atom other thancarbon and hydrogen that can be bound to carbon. A“heteroatom-containing group” is a hydrocarbon radical that contains aheteroatom and may contain one or more of the same or differentheteroatoms. In one embodiment, a heteroatom-containing group is ahydrocarbyl group containing from 1 to 3 atoms selected from the groupconsisting of boron, aluminum, silicon, germanium, nitrogen,phosphorous, oxygen and sulfur. Non-limiting examples ofheteroatom-containing groups include radicals of imines, amines, oxides,phosphines, ethers, ketones, oxoazolines heterocyclics, oxazolines, andthioethers.

As used herein, “heterocyclic” refers to ring systems having a carbonbackbone that comprise from 1 to 3 atoms selected from the groupconsisting of boron, aluminum, silicon, germanium, nitrogen,phosphorous, oxygen and sulfur, unless the heteroatom (non carbon atom)is described.

As used herein, an “alkylcarboxylate”, “arylcarboxylate”, and“alkylarylcarboxylate” is an alkyl, aryl, and alkylaryl, respectively,that possesses a carboxyl group in any position. Examples includeC₆H₅CH₂C(O)O⁻, and CH₃C(O)O⁻.

As used herein, the term “substituted” means that the group followingthat term possesses at least one moiety in place of one or morehydrogens in any position, the moieties selected from such groups ashalogen radicals (esp., Cl, F, Br), hydroxyl groups, carbonyl groups,carboxyl groups, amine groups, phosphine groups, alkoxy groups, phenylgroups, naphthyl groups, C₁ to C₁₀ alkyl groups, C₂ to C₁₀ alkenylgroups, and combinations thereof. Examples of substituted alkyls andaryls includes, but are not limited to, acyl radicals, alkylaminoradicals, alkoxy radicals, aryloxy radicals, alkylthio radicals,dialkylamino radicals, alkoxycarbonyl radicals, aryloxycarbonylradicals, carbomoyl radicals, alkyl- and dialkyl-carbamoyl radicals,acyloxy radicals, acylamino radicals, arylamino radicals, andcombinations thereof.

As used herein, structural formulas are employed as is commonlyunderstood in the chemical arts; lines (“—”) used to representassociations between a metal atom (“M”, Group 3 to Group 12 atoms) and aligand, ligand atom or atom (e.g., cyclopentadienyl, nitrogen, oxygen,halogen ions, alkyl), as well as the phrases “associated with”, “bondedto” and “bonding”, are not limited to representing a certain type ofchemical bond, as these lines and phrases are meant to represent a“chemical bond”; a “chemical bond” defined as an attractive forcebetween atoms that is strong enough to permit the combined aggregate tofunction as a unit, or “compound”.

A certain stereochemistry for a given structure or part of a structureshould not be implied unless so stated for a given structure or apparentby use of commonly used bonding symbols such as by dashed lines and/orheavy lines.

Unless stated otherwise, no embodiment of the present invention isherein limited to the oxidation state of the metal atom “M” as definedbelow in the individual descriptions and examples that follow. Theligation of the metal atom “M” is such that the compounds describedherein are neutral, unless otherwise indicated.

Ziegler-Natta Catalyst Component

The catalyst composition includes a first catalyst component, which maybe (or includes) a non-metallocene compound. However, it is contemplatedthat for certain applications the first catalyst component mayalternatively be a metallocene compound, or even one of themetallocene-type catalyst compounds identified below that is differentin structure from the second catalyst component as described herein. Inan embodiment, the first catalyst component may be a Ziegler-Nattacatalyst compound, such as disclosed in ZIEGLER CATALYSTS 363-386 (G.Fink, R. Mulhaupt and H. H. Brintzinger, eds., Springer-Verlag 1995);and in EP 103 120; EP 102 503; EP 0 231 102; EP 0 703 246; RE 33,683;U.S. Pat. No. 4,302,565; U.S. Pat. No. 5,518,973; U.S. Pat. No.5,525,678; U.S. Pat. No. 5,288,933; U.S. Pat. No. 5,290,745; U.S. Pat.No. 5,093,415 and U.S. Pat. No. 6,562,905. Examples of such catalystsinclude those comprising Group 4, 5 or 6 transition metal oxides,alkoxides and halides, or oxides, alkoxides and halide compounds oftitanium, zirconium or vanadium; optionally in combination with amagnesium compound, internal and/or external electron donors (alcohols,ethers, siloxanes), aluminum or boron alkyl and alkyl halides, andinorganic oxide supports.

The Ziegler-Natta catalyst is combined with a support material in oneembodiment, either with or without the second catalyst component. Thefirst catalyst component can be combined with, placed on or otherwiseaffixed to a support in a variety of ways. In one of those ways, aslurry of the support in a suitable non-polar hydrocarbon diluent iscontacted with an organomagnesium compound, which then dissolves in thenon-polar hydrocarbon diluent of the slurry to form a solution fromwhich the organomagnesium compound is then deposited onto the carrier.The organomagnesium compound can be represented by the formula RMgR′,where R′ and R are the same or different C₂-C₁₂ alkyl groups, or C₄-C₁₀alkyl groups, or C₄-C₈ alkyl groups. In at least one embodiment, theorganomagnesium compound is dibutyl magnesium. In one embodiment, theamount of organomagnesium compound included in the silica slurry is onlythat which will be deposited, physically or chemically, onto thesupport, for example, being bound to the hydroxyl groups on the support,and no more than that amount, since any excess organomagnesium compoundmay cause undesirable side reactions. Routine experimentation can beused to determine the optimum amount of organomagnesium compound. Forexample, the organomagnesium compound can be added to the slurry whilestirring the slurry, until the organomagnesium compound is detected inthe support solvent. Alternatively, the organomagnesium compound can beadded in excess of the amount that is deposited onto the support, inwhich case any undeposited excess amount can be removed by filtrationand washing. The amount of organomagnesium compound (moles) based on theamount of dehydrated silica (grams) generally range from 0.2 mmol/g to 2mmol/g in an embodiment.

In one embodiment the Ziegler-Natta catalyst, optionally including theorganomagnesium compound, is contacted with an electron donor, such astetraethylorthosilicate (TEOS) or an organic alcohol having the formulaR″OH, where R″ is a C₁-C₁₂ alkyl group, or a C₁ to C₈ alkyl group, or aC₂ to C₄ alkyl group, and/or an ether or cyclic ether such astetrahydrofuran. In an embodiment, R″OH is n-butanol. The amount oforganic alcohol is used in an amount effective to provide an R″OH:Mgmol/mol ratio of from 0.2 to 1.5, or from 0.4 to 1.2, or from 0.6 to1.1, or from 0.9 to 1.0.

The organomagnesium and alcohol-treated slurry is contacted with anon-metallocene transition metal compound. Suitable non-metallocenetransition metal compounds are compounds of Group 4, 5 and 6 metals thatare soluble in the non-polar hydrocarbon used to form the silica slurryin an embodiment. Non-limiting examples of suitable Group 4, 5 or 6transition metal compounds include, for example, titanium and vanadiumhalides, oxyhalides or alkoxyhalides, such as titanium tetrachloride(TiCl₄), vanadium tetrachloride (VCl₄) and vanadium oxytrichloride(VOCl₃), and titanium and vanadium alkoxides, wherein the alkoxidemoiety has a branched or unbranched alkyl group of 1 to 20 carbon atoms,or 1 to 6 carbon atoms. Mixtures of such transition metal compounds mayalso be used. The amount of non-metallocene transition metal compoundused is sufficient to give a transition metal to magnesium mol/mol ratioof from 0.3 to 1.5, or from 0.5 to 0.8. The diluent can then be removedin a conventional manner, such as by evaporation or filtering, to obtainthe dry, supported first catalyst component.

The first and second catalyst components may be contacted with thesupport in any order. In an embodiment of the invention, the firstcatalyst component is reacted first with the support as described above,followed by contacting this supported first catalyst component with asecond catalyst component.

Metallocene Catalyst Component

The catalyst system useful in the present invention includes at leastone metallocene catalyst component as described herein. Metallocenecatalyst compounds are generally described throughout in, for example, 1& 2 METALLOCENE-BASED POLYOLEFINS (John Scheirs & W. Kaminsky eds., JohnWiley & Sons, Ltd. 2000); G. G. Hlatky in 181 COORDINATION CHEM. REV.243-296 (1999) and in particular, for use in the synthesis ofpolyethylene in 1 METALLOCENE-BASED POLYOLEFINS 261-377 (2000). Themetallocene catalyst compounds as described herein include “halfsandwich” and “full sandwich” compounds having one or more Cp ligands(cyclopentadienyl and ligands isolobal to cyclopentadienyl) bound to atleast one Group 3 to Group 12 metal atom, and one or more leavinggroup(s) bound to the at least one metal atom. Hereinafter, thesecompounds will be referred to as “metallocenes” or “metallocene catalystcomponents”. The metallocene catalyst component is supported on asupport material in an embodiment as described further below, and may besupported with or without another catalyst component.

The Cp ligands are one or more rings or ring system(s), at least aportion of which includes π-bonded systems, such as cycloalkadienylligands and heterocyclic analogues. The ring(s) or ring system(s)typically comprise atoms selected from the group consisting of Groups 13to 16 atoms, and the atoms that make up the Cp ligands are selected fromthe group consisting of carbon, nitrogen, oxygen, silicon, sulfur,phosphorus, germanium, boron and aluminum and combinations thereof,wherein carbon makes up at least 50% of the ring members. Or, the Cpligand(s) are selected from the group consisting of substituted andunsubstituted cyclopentadienyl ligands, non-limiting examples of whichinclude cyclopentadienyl, indenyl, fluorenyl and other structures.Further non-limiting examples of such ligands include cyclopentadienyl,cyclopentaphenanthreneyl, indenyl, benzindenyl, fluorenyl,octahydrofluorenyl, cyclooctatetraenyl, cyclopentacyclododecene,phenanthrindenyl, 3,4-benzofluorenyl, 9-phenylfluorenyl,8-H-cyclopent[a]acenaphthylenyl, 7H-dibenzofluorenyl,indeno[1,2-9]anthrene, thiophenoindenyl, thiophenofluorenyl,hydrogenated versions thereof (e.g., 4,5,6,7-tetrahydroindenyl, or“H₄Ind”), substituted versions thereof (as described in more detailbelow), and heterocyclic versions thereof.

The metal atom “M” of the metallocene catalyst compound, as describedthroughout the specification and claims, may be selected from the groupconsisting of Groups 3 through 12 atoms and lanthanide Group atoms inone embodiment; and selected from the group consisting of Groups 3through 10 atoms in another embodiment, and selected from the groupconsisting of Sc, Ti, Zr, Hf, V, Nb, Ta, Mn, Re, Fe, Ru, Os, Co, Rh, Ir,and Ni in another embodiment; and selected from the group consisting ofGroups 4, 5 and 6 atoms in another embodiment, and Ti, Zr, Hf atoms inanother embodiment, and Zr in another embodiment. The oxidation state ofthe metal atom “M” may range from 0 to +7 in one embodiment; and inanother embodiment, is +1, +2, +3, +4 or +5; and in another embodimentis +2, +3 or +4. The groups bound the metal atom “M” are such that thecompounds described below in the formulas and structures areelectrically neutral, unless otherwise indicated. The Cp ligand(s) format least one chemical bond with the metal atom M to form the“metallocene catalyst compound”. The Cp ligands are distinct from theleaving groups bound to the catalyst compound in that they are nothighly susceptible to substitution/abstraction reactions.

In one aspect of the invention, the one or more metallocene catalystcomponents of the invention are represented by the formula (I):Cp^(A)Cp^(B)MX_(n)  (I)wherein M is as described above; each X is chemically bonded to M; eachCp group is chemically bonded to M; and n is 0 or an integer from 1 to4, and either 1 or 2 in an embodiment.

The ligands represented by Cp^(A) and Cp^(B) in formula (I) may be thesame or different cyclopentadienyl ligands or ligands isolobal tocyclopentadienyl, either or both of which may contain heteroatoms andeither or both of which may be substituted by a group R. In oneembodiment, Cp^(A) and Cp^(B) are independently selected from the groupconsisting of cyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl,and substituted derivatives of each.

Independently, each Cp^(A) and Cp^(B) of formula (I) may beunsubstituted or substituted with any one or combination of substituentgroups R. Non-limiting examples of substituent groups R as used instructure (I) as well as ring substituents in structures (Va-d (hereinbelow)) include groups selected from the group consisting of hydrogenradicals, alkyls, alkenyls, alkynyls, cycloalkyls, aryls, acyls, aroyls,alkoxys, aryloxys, alkylthiols, dialkylamines, alkylamidos,alkoxycarbonyls, aryloxycarbonyls, carbomoyls, alkyl- anddialkyl-carbamoyls, acyloxys, acylaminos, aroylaminos, and combinationsthereof.

Other non-limiting examples of alkyl substituents R associated withformula (I) through (V) include methyl, ethyl, propyl, butyl, pentyl,hexyl, cyclopentyl, cyclohexyl, benzyl, phenyl, methylphenyl, andtert-butylphenyl groups, including all their isomers, for exampletertiary-butyl, and isopropyl. Other possible radicals includesubstituted alkyls and aryls such as, for example, fluoromethyl,fluroethyl, difluroethyl, iodopropyl, bromohexyl, chlorobenzyl andhydrocarbyl substituted organometalloid radicals includingtrimethylsilyl, trimethylgermyl, and methyldiethylsilyl; andhalocarbyl-substituted organometalloid radicals includingtris(trifluoromethyl)silyl, methylbis(difluoromethyl)silyl, andbromomethyldimethylgermyl; and disubstituted boron radicals includingdimethylboron for example; and disubstituted Group 15 radicals includingdimethylamine, dimethylphosphine, diphenylamine, methylphenylphosphine,Group 16 radicals including methoxy, ethoxy, propoxy, phenoxy,methylsulfide and ethylsulfide. Other substituents R include olefinssuch as but not limited to olefinically unsaturated substituentsincluding vinyl-terminated ligands, for example 3-butenyl, 2-propenyl,and 5-hexenyl. In one embodiment, at least two R groups, two adjacent Rgroups in one embodiment, are joined to form a ring structure havingfrom 3 to 30 atoms selected from the group consisting of carbon,nitrogen, oxygen, phosphorous, silicon, germanium, aluminum, boron andcombinations thereof. Also, a substituent group R group such as1-butanyl may form a bonding association to the element M.

Each X in the formula (I) above and for the formulas/structures (II)through (V) below is independently selected from the group consistingof: any leaving group in one embodiment; halogen ions, hydrides, C₁ toC₁₂ alkyls, C₂ to C₁₂ alkenyls, C₆ to C₁₂ aryls, C₇ to C₂₀ alkylaryls,C₁ to C₁₂ alkoxys, C₆ to C₁₆ aryloxys, C₇ to C₁₈ alkylaryloxys, C₁ toC₁₂ fluoroalkyls, C₆ to C₁₂ fluoroaryls, and C₁ to C₁₂heteroatom-containing hydrocarbons and substituted derivatives thereofin another embodiment; hydride, halogen ions, C₁ to C₆ alkyls, C₂ to C₆alkenyls, C₇ to C₁₈ alkylaryls, C₁ to C₆ alkoxys, C₆ to C₁₄ aryloxys, C₇to C₁₆ alkylaryloxys, C₁ to C₆ alkylcarboxylates, C₁ to C₆ fluorinatedalkylcarboxylates, C₆ to C₁₂ arylcarboxylates, C₇ to C₁₈alkylarylcarboxylates, C₁ to C₆ fluoroalkyls, C₂ to C₆ fluoroalkenyls,and C₇ to C₁₈ fluoroalkylaryls in another embodiment; hydride, chloride,fluoride, methyl, phenyl, phenoxy, benzoxy, tosyl, fluoromethyls andfluorophenyls in another embodiment; C₁ to C₁₂ alkyls, C₂ to C₁₂alkenyls, C₆ to C₁₂ aryls, C₇ to C₂₀ alkylaryls, substituted C₁ to C₁₂alkyls, substituted C₆ to C₁₂ aryls, substituted C₇ to C₂₀ alkylarylsand C₁ to C₁₂ heteroatom-containing alkyls, C₁ to C₁₂heteroatom-containing aryls and C₁ to C₁₂ heteroatom-containingalkylaryls in another embodiment; chloride, fluoride, C₁ to C₆ alkyls,C₂ to C₆ alkenyls, C₇ to C₁₈ alkylaryls, halogenated C₁ to C₆ alkyls,halogenated C₂ to C₆ alkenyls, and halogenated C₇ to C₁₈ alkylaryls inanother embodiment; fluoride, methyl, ethyl, propyl, phenyl,methylphenyl, dimethylphenyl, trimethylphenyl, fluoromethyls (mono-, di-and trifluoromethyls) and fluorophenyls (mono-, di-, tri-, tetra- andpentafluorophenyls) in another embodiment; and fluoride in anotherembodiment.

Other non-limiting examples of X groups in formula (I) include amines,amido compounds, phosphines, ethers, carboxylates, dienes, hydrocarbonradicals having from 1 to 20 carbon atoms, fluorinated hydrocarbonradicals (e.g., —C₆F₅ (pentafluorophenyl)), fluorinatedalkylcarboxylates (e.g., CF₃C(O)O⁻), hydrides and halogen ions andcombinations thereof. Other examples of X ligands include alkyl groupssuch as cyclobutyl, cyclohexyl, methyl, heptyl, tolyl, trifluoromethyl,tetramethylene, pentamethylene, methylidene, methyoxy, ethyoxy, propoxy,phenoxy, bis(N-methylanilide), dimethylamide, and dimethylphosphideradicals. In one embodiment, two or more X's form a part of a fused ringor ring system.

In another aspect of the invention, the metallocene catalyst componentincludes those of formula (I) where Cp^(A) and Cp^(B) are bridged toeach other by at least one bridging group, (A), such that the structureis represented by formula (II):Cp^(A)(A)Cp^(B)MX_(n)  (II)

These bridged compounds represented by formula (II) are known as“bridged metallocenes”. Cp^(A), Cp^(B), M, X and n in structure (II) areas defined above for formula (I); and wherein each Cp ligand ischemically bonded to M, and (A) is chemically bonded to each Cp.Non-limiting examples of bridging group (A) include divalent hydrocarbongroups containing at least one Group 13 to 16 atom, such as but notlimited to at least one of a carbon, oxygen, nitrogen, silicon,aluminum, boron, germanium and tin atom and combinations thereof;wherein the heteroatom may also be C₁ to C₁₂ alkyl or aryl substitutedto satisfy neutral valency. The bridging group (A) may also containsubstituent groups R as defined above (for formula (I)) includinghalogen radicals and iron. Other non-limiting examples of bridging group(A) are represented by C₁ to C₆ alkylenes, substituted C₁ to C₆alkylenes, oxygen, sulfur, R′₂C═, R′₂Si═, —Si(R′)₂Si(R′₂#, R′₂Ge═, R′P═(wherein “═” represents two chemical bonds), where R′ is independentlyselected from the group consisting of hydride, hydrocarbyl, substitutedhydrocarbyl, halocarbyl, substituted halocarbyl, hydrocarbyl-substitutedorganometalloid, halocarbyl-substituted organometalloid, disubstitutedboron, disubstituted Group 15 atoms, substituted Group 16 atoms, andhalogen radical; and wherein two or more R′ may be joined to form a ringor ring system. In one embodiment, the bridged metallocene catalystcomponent of formula (II) has two or more bridging groups (A).

Other non-limiting examples of bridging group (A) include methylene,ethylene, ethylidene, propylidene, isopropylidene, diphenylmethylene,1,2-dimethylethylene, 1,2-diphenylethylene, 1,1,2,2-tetramethylethylene,dimethylsilyl, diethylsilyl, methyl-ethylsilyl,trifluoromethylbutylsilyl, bis(trifluoromethyl)silyl, di(n-butyl)silyl,di(n-propyl)silyl, di(i-propyl)silyl, di(n-hexyl)silyl,dicyclohexylsilyl, diphenylsilyl, cyclohexylphenylsilyl,t-butylcyclohexylsilyl, di(t-butylphenyl)silyl, di(p-tolyl)silyl and thecorresponding moieties wherein the Si atom is replaced by a Ge or a Catom; dimethylsilyl, diethylsilyl, dimethylgermyl and diethylgermyl.

In another embodiment, bridging group (A) may also be cyclic,comprising, for example 4 to 10, 5 to 7 ring members in anotherembodiment. The ring members may be selected from the elements mentionedabove, from one or more of B, C, Si, Ge, N and O in another embodiment.Non-limiting examples of ring structures which may be present as or partof the bridging moiety are cyclobutylidene, cyclopentylidene,cyclohexylidene, cycloheptylidene, cyclooctylidene and the correspondingrings where one or two carbon atoms are replaced by at least one of Si,Ge, N and O. The bonding arrangement between the ring and the Cp groupsmay be either cis-, trans-, or a combination.

The cyclic bridging groups (A) may be saturated or unsaturated and/orcarry one or more substituents and/or be fused to one or more other ringstructures. If present, the one or more substituents are selected fromthe group consisting of hydrocarbyl (e.g., alkyl such as methyl) andhalogen (e.g., F, Cl) in one embodiment. The one or more Cp groups whichthe above cyclic bridging moieties may optionally be fused to may besaturated or unsaturated and are selected from the group consisting ofthose having 4 to 10, or 5, 6 or 7 ring members (selected from the groupconsisting of C, N, O and S in another embodiment), for example,cyclopentyl, cyclohexyl and phenyl. Moreover, these ring structures maythemselves be fused such as, for example, in the case of a naphthylgroup. Moreover, these (optionally fused) ring structures may carry oneor more substituents. Illustrative, non-limiting examples of thesesubstituents are hydrocarbyl (including in some embodiments, alkyl)groups and halogen atoms.

The ligands Cp^(A) and Cp^(B) of formulae (I) and (II) are differentfrom each other in one embodiment, and the same in another embodiment.

In yet another aspect of the invention, the metallocene catalystcomponents include bridged mono-ligand metallocene compounds (e.g., monocyclopentadienyl catalyst components). In this embodiment, the at leastone metallocene catalyst component is a bridged “half-sandwich”metallocene as in, for example, U.S. Pat. No. 5,055,438, represented bythe formula (III):Cp^(A)(A)QMX_(n)  (III)wherein Cp^(A) is defined above and is bound to M; (A) is a bridginggroup bonded to Q and Cp^(A); and wherein an atom from the Q group isbonded to M; and n is 0 or an integer from 1 to 3; 1 or 2 in anotherembodiment. In formula (III) above, Cp^(A), (A) and Q may form a fusedring system. The X groups and n of formula (III) are as defined above informula (I) and (II). In one embodiment, Cp^(A) is selected from thegroup consisting of cyclopentadienyl, indenyl, tetrahydroindenyl,fluorenyl, substituted versions thereof, and combinations thereof.

In formula (III), Q is a heteroatom-containing ligand in which thebonding atom (the atom that is bonded with the metal M) is selected fromthe group consisting of Group 15 atoms and Group 16 atoms in oneembodiment, and selected from the group consisting of nitrogen,phosphorus, oxygen or sulfur atom in another embodiment, and nitrogenand oxygen in another embodiment. Non-limiting examples of Q groupsinclude alkylamines, arylamines, mercapto compounds, ethoxy compounds,carboxylates (e.g., pivalate), carbamates, azenyl, azulene, pentalene,phosphoyl, phosphinimine, pyrrolyl, pyrozolyl, carbazolyl, borabenzeneother compounds comprising Group 15 and Group 16 atoms capable ofbonding with M.

In yet another aspect of the invention, the at least one metallocenecatalyst component is an unbridged “half sandwich” metallocenerepresented by the formula (IVa):Cp^(A)MQ_(q)X_(n)  (IVa)wherein Cp^(A) is defined as for the Cp groups in (I) and is a ligandthat is bonded to M; each Q is independently bonded to M; Q is alsobound to Cp^(A) in one embodiment; X is a leaving group as describedabove in (I); n ranges from 0 to 3, and is 1 or 2 in one embodiment; qranges from 0 to 3, and is 1 or 2 in one embodiment. In one embodiment,Cp^(A) is selected from the group consisting of cyclopentadienyl,indenyl, tetrahydroindenyl, fluorenyl, substituted version thereof, andcombinations thereof.

In formula (IVa), Q is selected from the group consisting of ROO⁻, RO—,R(O)—, —NR—, —CR₂—, —S—, —NR₂, —CR₃, —SR, —SiR₃, —PR₂, —H, andsubstituted and unsubstituted aryl groups, wherein R is selected fromthe group consisting of C₁ to C₆ alkyls, C₆ to C₁₂ aryls, C₁ to C₆alkylamines, C₆ to C₁₂ alkylarylamines, C₁ to C₆ alkoxys, and C₆ to C₁₂aryloxys. Non-limiting examples of Q include C₁ to C₁₂ carbamates, C₁ toC₁₂ carboxylates (e.g., pivalate), C₂ to C₂₀ allyls, and C₂ to C₂₀heteroallyl moieties.

Described another way, the “half sandwich” metallocenes above can bedescribed as in formula (IVb), such as described in, for example, U.S.Pat. No. 6,069,213:Cp^(A)M(Q₂GZ)X_(n)orT(Cp^(A)M(Q₂GZ)X_(n))_(m)  (IVb)

-   wherein M, Cp^(A), X and n are as defined above;-   Q₂GZ forms a polydentate ligand unit (e.g., pivalate), wherein at    least one of the Q groups form a bond with M, and is defined such    that each Q is independently selected from the group consisting of    —O—, —NR—, —CR₂— and —S—; G is either carbon or silicon; and Z is    selected from the group consisting of R, —OR, —NR₂, —CR₃, —SR,    —SiR₃, —PR₂, and hydride, providing that when Q is —NR—, then Z is    selected from the group consisting of —OR, —NR₂, —SR, —SiR₃, —PR₂;    and provided that neutral valency for Q is satisfied by Z; and    wherein each R is independently selected from the group consisting    of C₁ to C₁₀ heteroatom containing groups, C₁ to C₁₀ alkyls, C₆ to    C₁₂ aryls, C₆ to C₁₂ alkylaryls, C₁ to C₁₀ alkoxys, and C₆ to C₁₂    aryloxys;-   n is 1 or 2 in an embodiment; and-   T is a bridging group selected from the group consisting of C₁, to    C₁₀ alkylenes, C₆ to C₁₂ arylenes and C₁ to C₁₀ heteroatom    containing groups, and C₆ to C₁₂ heterocyclic groups; wherein each T    group bridges adjacent “Cp^(A)M(Q₂GZ)X_(n)” groups, and is    chemically bonded to the Cp^(A) groups.

In formula (IVb), m is an integer from 1 to 7; m is an integer from 2 to6 in another embodiment.

In another aspect of the invention, the at least one metallocenecatalyst component can be described more in structures (Va), (Vb), (Vc),(Vd) (Ve) and (Vf):

-   wherein in structures (Va) to (Vf) M is selected from the group    consisting of Group 3 to Group 12 atoms, and selected from the group    consisting of Group 3 to Group 10 atoms in another embodiment, and    selected from the group consisting of Group 3 to Group 6 atoms in    another embodiment, and selected from the group consisting of Group    4 atoms in another embodiment, and selected from the group    consisting of Zr and Hf in another embodiment; and is Zr in another    embodiment;-   wherein Q in (Va-ii) is selected from the group consisting of    alkylenes, aryls, arylenes, alkoxys, aryloxys, amines, arylamines    (e.g., pyridyl) alkylamines, phosphines, alkylphosphines,    substituted alkyls, substituted aryls, substituted alkoxys,    substituted aryloxys, substituted amines, substituted alkylamines,    substituted phosphines, substituted alkylphosphines, carbamates,    heteroallyls, carboxylates (non-limiting examples of suitable    carbamates and carboxylates include trimethylacetate,    trimethylacetate, methylacetate, p-toluate, benzoate,    diethylcarbamate, and dimethylcarbamate), fluorinated alkyls,    fluorinated aryls, and fluorinated alkylcarboxylates; wherein the    saturated groups defining Q comprise from 1 to 20 carbon atoms in    one embodiment; and wherein the aromatic groups comprise from 5 to    20 carbon atoms in one embodiment; wherein each R* is independently:    selected from the group consisting of hydrocarbylenes and    heteroatom-containing hydrocarbylenes in one embodiment; and    selected from the group consisting of alkylenes, substituted    alkylenes and heteroatom-containing hydrocarbylenes in another    embodiment; and selected from the group consisting of C₁ to C₁₂    alkylenes, C₁ to C₁₂ substituted alkylenes, and C₁ to C₁₂    heteroatom-containing hydrocarbylenes in another embodiment; and    selected from the group consisting of C₁ to C₄ alkylenes in another    embodiment; and wherein both R* groups are identical in another    embodiment in structures (Vb-f);-   A is as described above for (A) in structure (II), and selected from    the group consisting of a chemical bond, —O—, —S—, —SO₂—, —NR—,    =SiR₂, =GeR₂, =SnR₂, —R₂SiSiR₂—, RP═, C₁ to C₁₂ alkylenes,    substituted C₁ to C₁₂ alkylenes, divalent C₄ to C₁₂ cyclic    hydrocarbons and substituted and unsubstituted aryl groups in one    embodiment; and selected from the group consisting of C₅ to C₈    cyclic hydrocarbons, —CH₂CH₂—, ═CR₂ and =SiR₂ in another embodiment;    wherein and R is selected from the group consisting of alkyls,    cycloalkyls, aryls, alkoxys, fluoroalkyls and heteroatom-containing    hydrocarbons in one embodiment; and R is selected from the group    consisting of C₁ to C₆ alkyls, substituted phenyls, phenyl, and C₁    to C₆ alkoxys in another embodiment; and R is selected from the    group consisting of methoxy, methyl, phenoxy, and phenyl in another    embodiment;-   wherein A may be absent in yet another embodiment, in which case    each R* is defined as for R¹-R¹³;-   each X is as described above in (I);-   n is an integer from 0 to 4, and from 1 to 3 in another embodiment,    and 1 or 2 in yet another embodiment; and-   R¹ through R¹³ (and R^(4′) through R⁷ and R^(10′) through R^(13′))    are independently: selected from the group consisting of hydrogen    radical, halogen radicals, C₁ to C₁₂ alkyls, C₂ to C₁₂ alkenyls, C₆    to C₁₂ aryls, C₇ to C₂₀ alkylaryls, C₁ to C₁₂ alkoxys, C₁ to C₁₂    fluoroalkyls, C₆ to C₁₂ fluoroaryls, and C₁ to C₁₂    heteroatom-containing hydrocarbons and substituted derivatives    thereof in one embodiment; selected from the group consisting of    hydrogen radical, fluorine radical, chlorine radical, bromine    radical, C₁ to C₆ alkyls, C₂ to C₆ alkenyls, C₇ to C₁₈ alkylaryls,    C₁ to C₆ fluoroalkyls, C₂ to C₆ fluoroalkenyls, C₇ to C₁₈    fluoroalkylaryls in another embodiment; and hydrogen radical,    fluorine radical, chlorine radical, methyl, ethyl, propyl,    isopropyl, butyl, isobutyl, tertiary butyl, hexyl, phenyl,    2,6-di-methylpheyl, and 4-tertiarybutylpheyl groups in another    embodiment; wherein adjacent R groups may form a ring, either    saturated, partially saturated, or completely saturated.

The structure of the metallocene catalyst component represented by (Va)may take on many forms such as disclosed in, for example, U.S. Pat. No.5,026,798, U.S. Pat. No. 5,703,187, and U.S. Pat. No. 5,747,406,including a dimer or oligomeric structure, such as disclosed in, forexample, U.S. Pat. No. 5,026,798 and U.S. Pat. No. 6,069,213.

In an embodiment of the metallocene represented in (Vd), R¹ and R² forma conjugated 6-membered carbon ring system that may or may not besubstituted.

Non-limiting examples of metallocene catalyst components consistent withthe description herein include:

-   cyclopentadienylzirconium X_(n),-   indenylzirconium X_(n),-   (1-methylindenyl)zirconium X_(n),-   (2-methylindenyl)zirconium X_(n),-   (1-propylindenyl)zirconium X_(n),-   (2-propylindenyl)zirconium X_(n),-   (1-butylindenyl)zirconium X_(n),-   (2-butylindenyl)zirconium X_(n),-   (methylcyclopentadienyl)zirconium X_(n),-   tetrahydroindenylzirconium X_(n),-   (pentamethylcyclopentadienyl)zirconium X_(n),-   cyclopentadienylzirconium X_(n),-   pentamethylcyclopentadienyltitanium X_(n),-   tetramethylcyclopentyltitanium X_(n),-   1,2,4-trimethylcyclopentadienylzirconium X_(n),-   dimethylsilyl(1,2,3,4-tetramethylcyclopentadienyl)(cyclopentadienyl)zirconium    X_(n),    dimethylsilyl(1,2,3,4-tetramethylcyclopentadienyl)(1,2,3-trimethylcyclopentadienyl)zirconium    X_(n),-   dimethylsilyl(1,2,3,4-tetramethylcyclopentadienyl)(1,2-dimethylcyclopentadienyl)zirconium    X_(n),-   dimethylsilyl(1,2,3,4-tetramethyl-cyclopentadienyl)(2-methylcyclopentadienyl)zirconium    X_(n),-   dimethylsilyl(cyclopentadienyl)(indenyl)zirconium X_(n),-   dimethylsilyl(2-methylindenyl)(fluorenyl)zirconium X_(n),-   diphenylsilyl(1,2,3,4-tetramethyl-cyclopentadienyl)(3-propylcyclopentadienyl)zirconium    X_(n),-   dimethylsilyl(1,2,3,4-tetramethylcyclopentadienyl)(3-t-butylcyclopentadienyl)zirconium    X_(n),-   dimethylgermyl(1,2-dimethylcyclopentadienyl)(3-isopropylcyclopentadienyl)zirconium    X_(n),-   dimethylsilyl(1,2,3,4-tetramethyl-cyclopentadienyl)(3-methylcyclopentadienyl)    zirconium X_(n),-   diphenylmethylidene(cyclopentadienyl)(9-fluorenyl)zirconium X_(n),-   diphenylmethylidene(cyclopentadienyl)(indenyl)zirconium X_(n),-   iso-propylidenebis(cyclopentadienyl)zirconium X_(n),-   iso-propylidene(cyclopentadienyl)(9-fluorenyl)zirconium X_(n),-   iso-propylidene(3-methylcyclopentadienyl)(9-fluorenyl)zirconium    X_(n),-   ethylenebis(9-fluorenyl)zirconium X_(n),-   meso-ethylenebis(1-indenyl)zirconium X_(n),-   ethylenebis(1-indenyl)zirconium X_(n),-   ethylenebis(2-methyl-1-indenyl)zirconium X_(n),-   ethylenebis(2-methyl-4,5,6,7-tetrahydro-1-indenyl)zirconium X_(n),-   ethylenebis(2-propyl-4,5,6,7-tetrahydro-1-indenyl)zirconium X_(n),-   ethylenebis(2-isopropyl-4,5,6,7-tetrahydro-1-indenyl)zirconium    X_(n),-   ethylenebis(2-butyl-4,5,6,7-tetrahydro-1-indenyl)zirconium X_(n),-   ethylenebis(2-isobutyl-4,5,6,7-tetrahydro-1-indenyl)zirconium X_(n),-   dimethylsilyl(4,5,6,7-tetrahydro-1-indenyl)zirconium X_(n),-   diphenyl(4,5,6,7-tetrahydro-1-indenyl)zirconium X_(n),-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium X_(n),-   dimethylsilylbis(cyclopentadienyl)zirconium X_(n),-   dimethylsilylbis(9-fluorenyl)zirconium X_(n),-   dimethylsilylbis(1-indenyl)zirconium X_(n),-   dimethylsilylbis(2-methylindenyl)zirconiurn X_(n),-   dimethylsilylbis(2-propylindenyl)zirconium X_(n),-   dimethylsilylbis(2-butylindenyl)zirconium X_(n),-   diphenylsilylbis(2-methylindenyl)zirconium X_(n),-   diphenylsilylbis(2-propylindenyl)zirconium X_(n),-   diphenylsilylbis(2-butylindenyl)zirconium X_(n),-   dimethylgermylbis(2-methylindenyl)zirconium X_(n).-   dimethylsilylbis(tetrahydroindenyl)zirconium X_(n),-   dimethylsilylbis(tetramethylcyclopentadienyl)zirconium X_(n),-   dimethylsilyl(cyclopentadienyl)(9-fluorenyl)zirconium X_(n),-   diphenylsilyl(cyclopentadienyl)(9-fluorenyl)zirconium X_(n),-   diphenylsilylbis(indenyl)zirconium X_(n),-   cyclotrimethylenesilyl(tetramethylcyclopentadienyl)(cyclopentadienyl)zirconium    X_(n).-   cyclotetramethylenesilyl(tetramethylcyclopentadienyl)(cyclopentadienyl)    zirconium X_(n),-   cyclotrimethylenesilyl(tetramethylcyclopentadienyl)(2-methylindenyl)zirconium    X_(n),-   cyclotrimethylenesilyl(tetramethylcyclopentadienyl)(3-methylcyclopentadienyl)zirconium    X_(n),-   cyclotrimethylenesilylbis(2-methylindenyl)zirconium X_(n),-   cyclotrimethylenesilyl(tetramethylcyclopentadienyl)(2,3,5-trimethylcyclopentadienyl)zirconium    X_(n),-   cyclotrimethylenesilylbis(tetramethylcyclopentadienyl)zirconium    X_(n),-   dimethylsilyl(tetramethylcyclopentadieneyl)(N-tert-butylamido)titanium    X_(n),-   bis(cyclopentadienyl)chromium X_(n),-   bis(cyclopentadienyl)zirconium X_(n),-   bis(n-butylcyclopentadienyl)zirconium X_(n),-   bis(n-dodecyclcyclopentadienyl)zirconium X_(n),-   bis(ethylcyclopentadienyl)zirconium X_(n),-   bis(iso-butylcyclopentadienyl)zirconium X_(n),-   bis(iso-propylcyclopentadienyl)zirconium X_(n),-   bis(methylcyclopentadienyl)zirconium X_(n),-   bis(n-oxtylcyclopentadienyl)zirconium X_(n),-   bis(n-pentylcyclopentadienyl)zirconium X_(n),-   bis(n-propylcyclopentadienyl)zirconium X_(n),-   bis(trimethylsilylcyclopentadienyl)zirconium X_(n),-   bis(1,3-bis(trimethylsilyl)cyclopentadienyl)zirconium X_(n),-   bis(1-ethyl-2-methylcyclopentadienyl)zirconium X_(n),-   bis(1-ethyl-3-methylcyclopentadienyl)zirconium X_(n),-   bis(pentamethylcyclopentadienyl)zirconium X_(n),-   bis(pentamethylcyclopentadienyl)zirconium X_(n),-   bis(1-propyl-3-methylcyclopentadienyl)zirconium X_(n),-   bis(1-n-butyl-3-methylcyclopentadienyl)zirconium X_(n),-   bis(1-isobutyl-3-methylcyclopentadienyl)zirconium X_(n),-   bis(1-propyl-3-butylcyclopentadienyl)zirconium X_(n),-   bis(1,3-n-butylcyclopentadienyl)zirconium X_(n),-   bis(4,7-dimethylindenyl)zirconium X_(n),-   bis(indenyl)zirconium X_(n),-   bis(2-methylindenyl)zirconium X_(n),-   cyclopentadienylindenylzirconium X_(n),-   bis(n-propylcyclopentadienyl)haffnium X_(n),-   bis(n-butylcyclopentadienyl)haffnium X_(n),-   bis(n-pentylcyclopentadienyl)haffnium X_(n),-   (n-propyl cyclopentadienyl)(n-butyl cyclopentadienyl)hafnium X_(n),-   bis[(2-trimethylsilylethyl)cyclopentadienyl]hafnium X_(n),-   bis(trimethylsilyl cyclopentadienyl)hafnium X_(n),-   bis(2-n-propylindenyl)hafnium X_(n),-   bis(2-n-butylindenyl)hafnium X_(n),-   dimethylsilylbis(n-propylcyclopentadienyl)hafnium X_(n),-   dimethylsilylbis(n-butylcyclopentadienyl)hafnium X_(n),-   bis(9-n-propylfluorenyl)hafnium X_(n),-   bis(9-n-butylfluorenyl)hafnium X_(n),-   (9-n-propylfluorenyl)(2-n-propylindenyl)hafnium X_(n),-   bis(1-n-propyl-2-methylcyclopentadienyl)hafnium X_(n),-   (n-propylcyclopentadienyl)(1-n-propyl-3-n-butylcyclopentadienyl)hafnium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(cyclopropylamido)titanium    X_(n),-   dimethylsilyl(tetramethyleyclopentadienyl)(cyclobutylamido)titanium    X_(n),-   dimethylsilyl(tetramethyleyclopentadienyl)(cyclopentylamido)titanium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(cyclohexylamido)titanium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(cycloheptylamido)titanium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(cyclooctylamido)titanium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(cyclononylamido)titanium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(cyclodecylamido)titanium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(cycloundecylamido)titanium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(cyclododecylamido)titanium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(sec-butylamido)titanium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(n-octylamido)titanium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(n-decylamido)titanium    X_(n),-   dimethylsilyl(tetramethylcyclopentadienyl)(n-octadecylamido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(cyclopropylamido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(cyclobutylamido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(cyclopentylamido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(cyclohexylamido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(cycloheptylamido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(cyclooctylamido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(cyclononylamido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(cyclodecylainido)titanium,    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(cycloundecylanido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(cyclododecylatido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(sec-butylamido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(n-octylamido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(n-decylamido)titanium    X_(n),-   methylphenylsilyl(tetramethylcyclopentadienyl)(n-octadecylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(cyclopropylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(cyclobutylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(cyclopentylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(cyclohexylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(cycloheptylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(cyclooctylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(cyclononylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(cyclodecylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(cycloundecylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(cyclododecylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(sec-butylamido)titanium    X_(n),-   diphenylsilyl(tetramethyleyclopentadienyl)(n-octylamido)titanium    X_(n),-   diphenylsilyl(tetramethyleyclopentadienyl)(n-decylamido)titanium    X_(n),-   diphenylsilyl(tetramethylcyclopentadienyl)(n-octadecylamido)titanium    X_(n), and-   derivatives thereof.

By “derivatives thereof”, it is meant any substitution or ring formationas described above for structures (Va-f); and replacement of the metal“M” (Cr, Zr, Ti or Hf) with an atom selected from the group consistingof Cr, Zr, Hf and Ti; and replacement of the “X” group with any of C₁ toC₅ alkyls, C₆ aryls, C₆ to C₁₀ alkylaryls, fluorine or chlorine; n is 1,2 or 3.

It is contemplated that the metallocene catalyst's components describedabove include their structural or optical or enantiomeric isomers(racemic mixture), and may be a pure enantiomer in one embodiment.

As used herein, a single, bridged, asymmetrically substitutedmetallocene catalyst component having a racemic and/or meso isomer doesnot, itself, constitute at least two different bridged, metallocenecatalyst components. In an embodiment, the metallocenes described hereinare in their racemic form.

The “metallocene catalyst component” useful in the present invention maycomprise any combination of any “embodiment” described herein.

EXAMPLES

In certain embodiments (as described in these Examples) of the inventionthe catalyst was prepared in the following manner: silica supportmaterial, Davison Sylopol® 955 Silica was used. The silicas weredehydrated at a temperature of 875° C. Then, for each sample, anon-metallocene catalyst was combined with the dehydrated silica. Thatis, for each sample, 500 grams of the respective dehydrated silica wereadded into a 5-liter, 3-neck round bottom flask enclosed in an N₂ glovebox. Anhydrous hexane (2500 ml) was then added into the flask, making asilica/hexane slurry. The slurry was heated to a temperature of 54° C.while under constant stirring, and 380 grams of a 15 wt. % solution ofdibutyl magnesium was added to the slurry over a period of 20 minutes.The slurry was then allowed to stand for an additional 30 minutes.Butanol (27.4 grams) was diluted to volume with hexane in a 125 mlvolumetric flask. The entire 125 ml of diluted butanol solution wasadded dropwise into the flask containing the slurry, and then the slurrywas held at a temperature of 54° C. for 30 minutes while under constantagitation. The amount of butanol may be varied, depending upon thedesired concentrations. Titanium tetrachloride (41.0 grams) was dilutedto volume with hexane in a 125 ml volumetric flask. The entire 125 ml ofdiluted titanium tetrachloride solution was then added dropwise into theflask containing the slurry. Following the addition of the solution, theslurry was allowed to stand for about 30 minutes at a temperature of 54°C. The slurry was then allowed to cool to ambient temperature.

The metallocene catalyst compound was then added to the sample oftitanium tetrachloride-treated dehydrated silica. First, 673 grams of a30 wt. % solution of methylaluminoxane (MAO) in toluene was added to anew flask in an N₂ glove box. 13.72 grams of the metallocenebis-n-butyl-cyclopentadienyl zirconium difluoride was added into the MAOsolution, and the mixture was stirred until all of the solids weredissolved. Next, the MAO/Metallocene mixture was slowly added into theflask containing the previously prepared titanium reaction slurry over aperiod of one hour. Toluene (50 ml) was used to wash the residualMAO/Metallocene mixture remaining in the flask into the flask containingthe reaction slurry. The Al/Zr molar ratio (Al from MAO) may range from90 to 110; the Ti/Zr molar ratio was 6. Each resulting mixture thatincluded the respective bimetallic catalyst sample was then held atambient temperature for a period of one hour. Afterward, each mixturewas dried using a rotary vaporizer, followed by removing most of thehexanes using a vacuum pressure of 21 mmHg at a temperature of 52° C.The high boiling point toluene was subsequently removed using a vacuumpressure of 28 mmHg at a temperature of 70° C. The final driedbimetallic catalyst appears brown in color as a free flowing solid. Eachsample was used in a separate polymerization run in a gas phase reactor,under the conditions identified in the Tables to form a polyethylenepolymer composition. This example procedure is capable of beingscaled-up by 250 to 1000 times these amounts listed. In each case,addition of water to the reactor was used to stimulate a change inreaction conditions.

Table 1, below, contains the data used in FIG. 2 related to thecomparison of hexene leading indicators. Terms are defined in Example 1.TABLE 1 Polymer production LI rate LI_(SBA,T) LI_(simple) Day/Time FR₁GR₁ β (Example 1) (T/hr) WF_(SBA) (Comparative ex 1) (Comparative ex 2)Day 1 14:00 0.0135 0.0070 0.021407 1.9341 29.81 0.0070 1.937 1.940 Day 114:08 0.0135 0.0070 0.021559 1.9343 29.60 0.0070 1.937 1.939 Day 1 14:160.0135 0.0070 0.021347 1.9348 29.90 0.0070 1.937 1.939 Day 1 14:240.0135 0.0070 0.020884 1.9352 30.57 0.0070 1.937 1.938 Day 1 14:320.0135 0.0070 0.021626 1.9355 29.51 0.0070 1.937 1.938 Day 1 14:400.0135 0.0070 0.021633 1.9357 29.50 0.0070 1.936 1.936 Day 1 14:480.0135 0.0070 0.021458 1.9358 29.74 0.0070 1.936 1.932 Day 1 14:560.0134 0.0070 0.021661 1.9357 29.46 0.0070 1.935 1.928 Day 1 15:000.0134 0.0070 0.021603 1.9356 29.54 0.0070 1.935 1.926 Day 1 15:080.0134 0.0070 0.021462 1.9348 29.74 0.0071 1.934 1.922 Day 1 15:160.0134 0.0070 0.021553 1.9335 29.61 0.0071 1.933 1.928 Day 1 15:240.0135 0.0070 0.021515 1.9318 29.66 0.0071 1.933 1.934 Day 1 15:320.0135 0.0070 0.021207 1.9303 30.10 0.0071 1.933 1.939 Day 1 15:400.0135 0.0070 0.021591 1.9299 29.56 0.0071 1.933 1.939 Day 1 15:480.0135 0.0070 0.021764 1.9304 29.32 0.0071 1.933 1.939 Day 1 15:560.0135 0.0070 0.021891 1.9314 29.15 0.0071 1.933 1.939 Day 1 16:000.0135 0.0070 0.021637 1.9319 29.49 0.0071 1.933 1.939 Day 1 16:080.0135 0.0070 0.021745 1.9328 29.35 0.0071 1.933 1.940 Day 1 16:160.0135 0.0070 0.021757 1.934 29.33 0.0071 1.934 1.940 Day 1 16:24 0.01350.0070 0.021596 1.934 29.55 0.0071 1.934 1.939 Day 1 16:32 0.0135 0.00700.021835 1.935 29.22 0.0071 1.934 1.937 Day 1 16:40 0.0135 0.00700.021953 1.935 29.06 0.0071 1.934 1.935 Day 1 16:48 0.0135 0.00700.021657 1.935 29.47 0.0071 1.933 1.933 Day 1 16:56 0.0135 0.00700.02167 1.935 29.45 0.0072 1.933 1.930 Day 1 17:00 0.0135 0.00700.021569 1.935 29.59 0.0072 1.933 1.929 Day 1 17:08 0.0135 0.00700.021343 1.934 29.90 0.0072 1.932 1.927 Day 1 17:16 0.0134 0.00700.021389 1.933 29.84 0.0072 1.932 1.925 Day 1 17:24 0.0135 0.00700.021062 1.932 30.31 0.0072 1.931 1.926 Day 1 17:32 0.0135 0.00700.021567 1.931 29.59 0.0072 1.931 1.928 Day 1 17:40 0.0135 0.00700.02146 1.930 29.74 0.0072 1.930 1.929 Day 1 17:48 0.0136 0.00700.021715 1.929 29.39 0.0072 1.930 1.941 Day 1 17:56 0.0136 0.00700.021357 1.929 29.88 0.0072 1.931 1.949 Day 1 18:00 0.0136 0.00700.021389 1.928 29.84 0.0073 1.931 1.949 Day 1 18:08 0.0136 0.00700.021638 1.930 29.49 0.0073 1.932 1.949 Day 1 18:16 0.0136 0.00700.021428 1.932 29.78 0.0073 1.933 1.943 Day 1 18:24 0.0135 0.00700.021445 1.935 29.76 0.0073 1.933 1.937 Day 1 18:32 0.0136 0.00700.021543 1.937 29.62 0.0073 1.933 1.941 Day 1 18:40 0.0136 0.0070 0.02121.939 30.11 0.0073 1.936 1.946 Day 1 18:48 0.0146 0.0070 0.021237 1.94130.06 0.0074 1.939 2.089 Day 1 18:56 0.0151 0.0070 0.020899 1.944 30.550.0074 1.953 2.159 Day 1 19:00 0.0153 0.0070 0.021514 1.945 29.66 0.00741.960 2.200 Day 1 19:08 0.0170 0.0070 0.020986 1.958 30.42 0.0074 1.9882.440 Day 1 19:16 0.0170 0.0072 0.020901 1.921 30.54 0.0074 1.946 2.358Day 1 19:24 0.0170 0.0072 0.021378 1.978 29.85 0.0074 1.970 2.364 Day 119:32 0.0170 0.0076 0.021127 1.936 30.21 0.0074 1.893 2.238 Day 1 19:400.0170 0.0076 0.021332 1.987 29.92 0.0075 1.916 2.239 Day 1 19:48 0.01690.0078 0.021159 1.957 30.17 0.0075 1.867 2.159 Day 1 19:56 0.0169 0.00810.021244 1.937 30.05 0.0075 1.835 2.101 Day 1 20:00 0.0169 0.00810.021179 1.949 30.14 0.0075 1.841 2.097 Day 1 20:08 0.0169 0.00810.021732 1.968 29.36 0.0075 1.851 2.092 Day 1 20:16 0.0170 0.00810.021582 1.983 29.57 0.0075 1.860 2.091 Day 1 20:24 0.0169 0.00810.021106 1.994 30.24 0.0076 1.869 2.084 Day 1 20:32 0.0170 0.00820.021624 2.003 29.51 0.0076 1.877 2.084 Day 1 20:40 0.0170 0.00820.021511 2.010 29.67 0.0076 1.885 2.081 Day 1 20:48 0.0170 0.00820.021689 2.019 29.42 0.0076 1.895 2.082 Day 1 20:56 0.0170 0.00820.021601 2.028 29.54 0.0076 1.905 2.083 Day 1 21:00 0.0171 0.00820.021262 2.032 30.02 0.0076 1.910 2.084 Day 1 21:08 0.0171 0.00820.021542 2.039 29.62 0.0076 1.920 2.085 Day 1 21:16 0.0171 0.00820.021459 2.045 29.74 0.0076 1.929 2.083 Day 1 21:24 0.0171 0.00820.021087 2.051 30.27 0.0076 1.938 2.083 Day 1 21:32 0.0169 0.00820.021581 2.055 29.57 0.0077 1.945 2.066 Day 1 21:40 0.0170 0.00820.021759 2.059 29.33 0.0077 1.952 2.076 Day 1 21:48 0.0171 0.00820.02134 2.060 29.91 0.0077 1.959 2.081 Day 1 21:56 0.0171 0.00820.021298 2.061 29.97 0.0077 1.966 2.080 Day 1 22:00 0.0171 0.00820.021969 2.062 29.04 0.0077 1.969 2.079 Day 1 22:08 0.0171 0.00820.02135 2.064 29.90 0.0077 1.975 2.078 Day 1 22:16 0.0171 0.00820.021163 2.066 30.16 0.0077 1.981 2.085 Day 1 22:24 0.0171 0.00820.021309 2.067 29.95 0.0077 1.986 2.077 Day 1 22:32 0.0170 0.00820.021295 2.068 29.97 0.0077 1.991 2.072 Day 1 22:40 0.0170 0.00820.021122 2.070 30.22 0.0077 1.995 2.070 Day 1 22:48 0.0170 0.00820.020904 2.070 30.54 0.0078 1.999 2.067 Day 1 22:56 0.0169 0.00820.021159 2.069 30.17 0.0078 2.002 2.060 Day 1 23:00 0.0169 0.00820.021644 2.069 29.48 0.0078 2.004 2.060 Day 1 23:08 0.0169 0.00820.021259 2.069 30.02 0.0078 2.007 2.059 Day 1 23:16 0.0169 0.00820.021097 2.066 30.26 0.0078 2.009 2.055 Day 1 23:24 0.0169 0.00820.021711 2.065 29.39 0.0078 2.011 2.054 Day 1 23:32 0.0169 0.00820.020931 2.063 30.50 0.0078 2.013 2.053 Day 1 23:40 0.0169 0.00820.020938 2.061 30.49 0.0078 2.015 2.053 Day 1 23:48 0.0169 0.00820.020757 2.059 30.76 0.0078 2.017 2.053 Day 1 23:56 0.0169 0.00820.02118 2.057 30.14 0.0078 2.018 2.056 Day 2 00:00 0.0170 0.00820.021148 2.056 30.18 0.0078 2.019 2.059 Day 2 00:08 0.0170 0.00820.02086 2.055 30.60 0.0078 2.021 2.064 Day 2 00:16 0.0171 0.00820.021048 2.054 30.33 0.0078 2.023 2.069 Day 2 00:24 0.0171 0.00830.020762 2.054 30.75 0.0078 2.026 2.071 Day 2 00:32 0.0171 0.00830.020585 2.055 31.02 0.0078 2.028 2.072 Day 2 00:40 0.0170 0.00830.021164 2.057 30.16 0.0078 2.029 2.056 Day 2 00:48 0.0170 0.00830.021141 2.058 30.19 0.0078 2.030 2.060 Day 2 00:56 0.0170 0.00830.020613 2.058 30.98 0.0078 2.031 2.063 Day 2 01:00 0.0171 0.00830.02084 2.057 30.63 0.0078 2.032 2.064 Day 2 01:08 0.0171 0.00830.020809 2.057 30.68 0.0078 2.034 2.067 Day 2 01:16 0.0171 0.00830.020805 2.057 30.69 0.0078 2.035 2.066 Day 2 01:24 0.0171 0.00830.020742 2.057 30.78 0.0078 2.036 2.064 Day 2 01:32 0.0170 0.00830.021093 2.059 30.26 0.0078 2.038 2.062 Day 2 01:40 0.0171 0.00830.020356 2.061 31.37 0.0078 2.041 2.064 Day 2 01:48 0.0171 0.00830.020753 2.063 30.76 0.0078 2.044 2.066 Day 2 01:56 0.0171 0.00830.02088 2.065 30.57 0.0078 2.046 2.068 Day 2 02:00 0.0171 0.00820.020824 2.066 30.66 0.0078 2.048 2.069 Day 2 02:08 0.0169 0.00820.020742 2.067 30.78 0.0078 2.050 2.055 Day 2 02:16 0.0169 0.00820.02075 2.069 30.77 0.0078 2.051 2.051 Day 2 02:24 0.0170 0.0082 0.0212.070 30.40 0.0078 2.053 2.061 Day 2 02:32 0.0171 0.0082 0.020547 2.06931.08 0.0078 2.055 2.075 Day 2 02:40 0.0170 0.0082 0.021241 2.068 30.050.0078 2.057 2.068 Day 2 02:48 0.0170 0.0082 0.020717 2.070 30.82 0.00782.059 2.065 Day 2 02:56 0.0169 0.0082 0.020429 2.071 31.26 0.0078 2.0602.062 Day 2 03:00 0.0169 0.0082 0.020788 2.072 30.71 0.0078 2.061 2.061Day 2 03:08 0.0170 0.0082 0.020895 2.073 30.55 0.0078 2.063 2.073 Day 203:16 0.0170 0.0082 0.020623 2.073 30.96 0.0078 2.065 2.070 Day 2 03:240.0170 0.0082 0.02042 2.074 31.27 0.0078 2.067 2.072 Day 2 03:32 0.01700.0082 0.021052 2.075 30.32 0.0078 2.068 2.070 Day 2 03:40 0.0170 0.00820.020904 2.076 30.54 0.0078 2.070 2.074 Day 2 03:48 0.0170 0.00820.020865 2.077 30.60 0.0078 2.071 2.079 Day 2 03:56 0.0170 0.00820.020829 2.078 30.65 0.0078 2.073 2.082

All of the following examples were carried out in a commercial-scalefluidized bed reactor, using a catalyst system as described above whichincludes a metallocene comprising a bis-n-butyl-cyclopentadienylzirconium difluoride based catalyst and titanium tetrachloride asdisclosed above. The polymer production rate was typically 25,000-35,000kg/hr. The primary monomer was ethylene, and the comonomer was 1-hexene.Gas phase concentrations of H₂, ethylene and 1-hexene were measuredusing a gas chromatograph as the gas analyzer. Flow index, I_(21.6),data were obtained according to ASTM D1238-01 Procedure B at condition190/21.6. I_(2.16) is determined by ASTM D1238-01 Procedure A atcondition 190/2.16. Similar determinations of flow index or otherrheological properties, using other testing protocols, such as DIN, arecontemplated, using analogous mathematical determinations to those thatare outlined herein utilizing ASTM procedures. The use of ASTMprocedures is an embodiment of the invention. Flow rates of H₂, water,ethylene and 1-hexene were measured using conventional flow meters orCoriolis mass flow meters. FI_(H) is determined from the formula:FI _(H)=ln(−0.33759+0.516577*ln(I _(21.6))−0.01523*(I _(21.6) /I_(2.16)))

This formula was derived from blend studies, where two polymers withknown I_(21.6) were blended together and then the combined I_(21.6) andI_(2.16) were measured. The known I_(21.6) of the higher molecularweight component (the FI_(H) by definition) was correlated with thecombined properties to develop the above formula.

EXAMPLE 1 1-Hexene Comonomer Residence Time Exponentially WeightedMoving Average Leading Indicator in a Polymerization

A leading indicator calculated using the calculation/equation (shown asLI Example 1 in FIG. 2) $\begin{matrix}{{LI} = {\frac{{FR}_{1}}{{GR}_{1}} = \frac{{(\beta)\left( {FR}_{2} \right)} + {\left( {1 - \beta} \right)\left( {FR}_{3} \right)}}{{GR}_{1}}}} & \left( {1a} \right)\end{matrix}$

Where GR₁=present value of either of the comonomer/ethylene gas ratio(in this example, the 1-hexene/ethylene ratio is used in this example)or the present value of the hydrogen/ethylene gas ratio at time T (now)in the reactor, as determined by analysis of the recycle stream. In theexamples that follow (Comparative Examples 1 & 2, as well as thisexample, Example 1), the 1-hexene ratio was used for GR₁.

Where FR₁=the present value of the flow ratio of either of thecomonomer/ethylene ratio or the present value of the hydrogen/ethyleneratio expressed as an exponentially weighted moving average (EWMA) attime T. In the examples that follow, as well as this example (Example 1,Comparative Examples 1 & 2), the 1-hexene/ethylene ratio was used forFR₁.

Where FR₂=the instantaneous Flow Ratio of the 1-hexene/ethylene flowratio td minutes prior to time step T. In this example, td=18 minutes,which represents the approximate cycle gas analyzer sample transporttime and ½ the cycle time of this analyzer.

Where FR₃=a EWMA using the comonomer or hydrogen residence time tdminutes prior to time step T−1. In the examples that follow, as well asthis example (Example 1, Comparative Examples 1 & 2), the1-hexene/ethylene ratio was used for FR₃.

β=1−exp(−T/(comonomer residence time)=an exponential weighting factor orfilter constant (based on comonomer or hydrogen residence time in thereactor) (here 1-hexene residence time was used)=exp(−Δt/τ), where:

-   Δt=the time step chosen to update the LI calculation (typically=1    minute); and-   τ=the residence time of the raw material (typically either comonomer    or hydrogen) that is used to calculate the LI (again, in this    instance, 1-hexene residence time was used); where the leading    indicator LI (Example 1) was calculated using the process data in    Table 1. The weighting factor β was based on 1-hexene residence time    in the reactor. The reactor variable that was changed was comonomer    (in this case, 1-hexene) flow ratio, FR, which was changed from    0.0135 to 0.0170 at time day 1, 1900 hours. The data in FIG. 2    illustrate the relatively monotonic correlation between the flow    index, Fl, and the leading indicator. It should be noted that the    sawtooth patterns are related to the gas chromatograph analysis    technique and are not a part of the mathematical treatment of the    data. Ignoring the sawtooth pattern, one can see that the leading    indicator (LI Example 1) is consistently moving in the same    direction as the flow index, a much better performance than shown by    the other two calculation methods.

COMPARATIVE EXAMPLE 1 Polymer Residence Time Exponentially WeightedMoving Average Leading Indicator in a Polymerization

The same reactor and materials from Example 1 were used to preparepolymers (again the data is shown in Table 1) but the leading Indicator,LI (comparative Example 1), used to control the reaction was based on adifferent mathematical model where the process was: (a) determining aflow ratio, FR, by dividing the flow rate of a comonomer, 1-hexene, bythe monomer flow rate, ethylene, into the reactor and (b) determiningthe instantaneous relative gas phase concentration ratio GR of the1-hexene concentration divided by the monomer (ethylene) concentration,respectively, in a recycle gas stream in the reactor; then defining asingle back average (SBA) leading indicator function, LI_(SBA,T) as:${LI}_{{SBA},T} = \frac{\left( {{WF}_{SBA} \times {FR}} \right) + {\left( {1 - {WF}_{SBA}} \right) \times {SBA}_{T - 1}}}{GR}$where LI_(SBA,T) is the Single Back Average leading indicator where theweighting factor WF is based on the average polymer residence time inthe reactor at time period T during the reaction;WF_(SBA)=1−exp(−T/(polymer residence time)).

Where polymer residence time=polymer weight in the reactor/polymerproduction rate.

FR is the average flow ratio of 1-hexene and ethylene into the reactor;GR is the instantaneous gas phase relative concentration ratio of the1-hexene and ethylene in the recycle gas stream of the reactor system;WF_(SBA) was the weighting factor that depends on the polymer residencetime in the reactor; and SBA_(T-1) is the single back average valueduring the previous time period.

This leading indicator (LI (comparative Example 1) is shown in FIG. 2,and as can be seen from the figure, it is far slower to react to processchanges than the leading indicator of example 1 (LI Example 1).

COMPARATIVE EXAMPLE 2 Simple (Flow Ratio/Gas Ratio) Leading Indicator

FIG. 2 additionally illustrates another LI function, LI_(simple)(comparative example 2), based on simple gas composition ratios andmonomer and comonomer flow ratios into the reactor, with no averaging ortime delays. This Example is based on the LI as disclosed WO 03/044061.This example illustrates that without proper mathematical weighting,this simple leading indicator value overshoots the predicted flow indexvalues and it can be inferred from these results that a reactor runningbased on controlling this leading indicator (LI_(simple) (comparativeexample 2) would produce polymer product having reduced sales valuesince an appreciable fraction of the product would not meetspecification for flow index, FI. The FI specification typicallyrequires FI to be within 20% of the target in order to sell for fullsales value.

The leading indicators were determined as a function of time, at8-minute intervals, over the measured course of the reaction. Table 1shows the same trend that is evident in the plot in FIG. 2.

The flow index, I_(21.6), and melt index, I_(2.16), were measured atseveral time points by taking a sample of the polymer product at thecorresponding time. The comparative results of the three LI's discussedimmediately above in relationship to the flow index, FI of anethylene-1-hexene copolymer are shown in FIG. 2 in conjunction with theleading indicator data for the three LI's to illustrate the unexpectedlypositive behavior of the inventive LI method (LI Example 1) inpredicting the FI as compared to the dramatically overshooting resultfor change in FI for the simple gas flow-monomer concentration LI (LIsimple (comparative example 2) and the negative predictive result of theLI_(SBA, T) (Comparative example 1) based on polymer residence times onthe FI.

In FIG. 2, the changes in leading indicators are evident very soon afterthe change in comonomer (1-hexene) flow ratio, FR, which was changedfrom 0.0135 to 0.0170 at time day 1, 1900 hours. But the full change inthe flow index of the polymer product is not evident until much later(Day 2, 0000 hours). This illustrates the benefit of using a leadingindicator, particularly the inventive leading indicator of Example 1,for reactor control of FI, rather than waiting for measured FI results.Further, the flow index data points are placed at the time the polymersample was taken. Determination of the flow index in a laboratoryactually took approximately an additional 1 to 2 hours. So without theleading indicator, much more off-specification polymer would be producedin the 1 to 2 hours it takes to analyze the flow index samples, then theadditional time caused by the process lag after corrective action istaken.

As noted in FIG. 2, the leading indicator based on a weighting factorusing comonomer residence time (LI example 1) is far more accurate andpredictive than the leading indicator based on the weighting factorusing the polymer residence time (LI SBA,T (comparative example 1),which in turn is far more accurate and predictive than the leadingindicator using no averaging. LI, simple (comparative example 2) As canbe seen from FIG. 2, using the Leading Indicator (LI_(SBA) comparativeexample 1) results in an indicator that is substantially different andperhaps misleading when compared to the leading indicator (LI Example 1)of embodiments of our invention. The difference between LI_(SBA)(comparative example 1) and the inventive leading indicator (LIexample 1) is a difference of averaging technique.

EXAMPLE 3 Impact of a Change in H2/C2 (Hydrogen/Ethylene) Gas Ratio onLeading Indicator Setpoint

The following Example relates to gas phase polymerization procedurescarried out in a fluidized bed reactor showing the method of calculatinga desired leading indicator target (LI_(T)) value to control a gas phasepolymerization reactor and thereby control the properties of a polymerproduct. TABLE 2 SIMULATED LEADING INDICATOR TARGETS H2/C2 LI target,H2/C2 mole LI target example 3, mole ratio, comparative with FI_(H)Process Time Sample Time FI, I21.6 MI, I2.16 FI_(T) LI LI_(P) ratio SBAFI_(HO) example 4 FI_(H) impact Day 3 12:00 9.000 1.77 1.76 0.00900.0090 0.50 1.801 0.50 1.801 Day 3 10:35 Day 3 10:35 8.13 0.086 9.0001.77 1.75 0.0090 0.0089 0.496 1.791 0.44 1.793 Day 3 09:00 Day 3 09:008.62 0.082 9.000 1.75 1.77 0.0090 0.0089 0.441 1.714 0.46 1.712 Day 306:30 Day 3 06:30 10.20 0.095 9.000 1.77 1.78 0.0090 0.0089 0.463 1.7480.50 1.744 Day 3 04:05 Day 3 04:05 9.34 0.094 9.000 1.78 1.77 0.00900.0089 0.497 1.730 0.51 1.731 Day 3 02:25 Day 3 02:25 9.64 0.097 9.0001.78 1.77 0.0090 0.0088 0.510 1.686 0.45 1.685 Day 3 00:30 Day 3 00:3010.40 0.095 9.000 1.77 1.76 0.0090 0.0088 0.452 1.800 0.52 1.798 Day 222:30 Day 2 22:30 8.33 0.090 9.000 1.76 1.76 0.0090 0.0088 0.517 1.7930.52 1.769 Day 2 20:30 Day 2 20:30 8.87 0.092 9.000 1.75 1.79 0.00900.0084 0.505 1.680 0.47 1.638 Day 2 18:35 Day 2 18:35 11.80 0.103 9.0001.79 1.83 0.0090 0.0077 0.446 1.855 0.47 1.843 Day 2 16:10 Day 2 16:108.73 0.085 9.000 1.83 1.84 0.0079 0.0076 0.459 1.833 0.39 1.826 Day 214:30 Day 2 14:30 8.83 0.078 9.000 1.83 1.82 0.0077 0.0075 0.388 1.9510.43 1.952 Day 2 12:35 Day 2 12:35 7.16 0.072 9.000 1.83 1.83 0.00750.0074 0.432 1.878 0.42 1.871 Day 2 10:35 Day 2 10:35 8.12 0.076 9.0001.83 1.82 0.0073 0.0073 0.415 1.834 0.38 1.825 Day 2 08:25 Day 2 08:258.73 0.076 9.000 1.81 1.82 0.0071 0.0072 0.378 1.830 0.40 1.824 Day 206:30 Day 2 06:30 8.84 0.079 9.000 1.82 1.82 0.0069 0.0071 0.400 1.8260.41 1.819 Day 2 04:05 Day 2 04:05 8.86 0.080 9.000 1.82 1.82 0.00680.0070 0.408 1.829 0.41 1.827 Day 2 02:30 Day 2 02:30 8.82 0.080 9.0001.82 1.82 0.0068 0.0070 0.410 1.833 0.36 1.834 Day 2 00:35 Day 2 00:358.74 0.074 9.000 1.82 1.82 0.0068 0.0070 0.362 1.830 0.39 1.829 Day 122:40 Day 1 22:40 8.80 0.078 9.000 1.82 1.82 0.0068 0.0070 0.393 1.8340.39 1.832

Table 2 provides the data used to construct FIG. 3.

First LI data, based on present and past reactor operating parameters,are obtained and past analysis of a polymer product produced in thereactor under past leading indicator parameters are also obtained andthen a new, best LI_(target)=LI_(T) is calculated that relates to adesired future polymer product where the LI_(T) is defined as:LI _(T)=(ln(FI _(T))−A ₁ −C′ ₁ ×FI _(H))/C′₂;

-   where A₁=ln(FI_(O))−C′₂×LI_(P)−C′₁×FI_(HO)-   where: FI_(T)=the target flow index of a polymer product that is    desired after adjustment of reaction conditions to a new leading    indicator. FI_(O) is the measured flow index of total polymer    produced according to the previous leading indicator reactor    conditions; FI_(HO) is the flow index of the higher molecular weight    polymer measured or calculated on polymer produced according to the    previous leading indicator conditions; C′₁ is a constant related to    the catalyst system, in this case equal to 3.386; LI_(P) or the    previous leading indicator, is the leading indicator calculated, by    a single back average technique (SBA), from the previous time period    for the time that FI_(O) and FI_(HO) measurements were performed.    FI_(H) is the flow index of the higher molecular weight polymer    predicted to be produced by the catalyst system under current    reactor parameters, at the time that the LI_(T) is recalculated. In    this case, FI_(H) prediction accounted for the change in H2/C2 that    was occurring. C′₂ is a constant related to the catalyst system, in    this case equal to 1.863. At least one reactor parameter is adjusted    to change the leading indicator toward the new LI_(T) utilizing    ethylene monomer and hexene comonomer, resulting in production of a    polyethylene-based polymer product. In this particular example, the    hydrogen/ethylene ratio is changed to achieve this result.

The fluidized bed was made up of polymer granules. During each run, thegaseous feed streams of ethylene and hydrogen were introduced upstreamof the reactor bed into a recycle gas line. The injections were upstreamof the recycle line heat exchanger and compressor. Liquid hexene andisopentane were introduced into the fluidized bed. Trimethylaluminum wasadded before the reactor bed into a recycle gas line in gaseous orliquid form. The individual flows of ethylene, hydrogen and hexenecomonomer were controlled to maintain target reactor conditions. Theconcentrations of gases were measured by an on-line chromatograph.

In each run, supported bimetallic catalyst was injected directly intothe fluidized bed using purified nitrogen. Catalyst injection rates wereadjusted to maintain approximately constant production rate. In eachrun, the catalyst used was made with silica dehydrated at 875° C., andmetallocene compound Cp₂MX₂ wherein each Cp is a n-butyl substitutedcyclopentadienyl ring, M is zirconium, and X is fluoride. The titaniumsource was TiCl₄.

During each run, the reacting bed of growing polymer particles wasmaintained in a fluidized state by a continuous flow of the make-up feedand recycle gas through the reaction zone. Each run utilized a targetreactor temperature (“Bed Temperature”), typically, a reactortemperature of about 203° F. or 95° C. During each run, reactortemperature was maintained at an approximately constant level byadjusting (up or down) the temperature of the recycle gas to accommodateany changes in the rate of heat generation due to the polymerization.

The reactor was stable with H2/C2 molar ratio of 0.0068. At TIME 1 (inTable 2, day 2, 0630 hours), and shown on FIG. 3, H2/C2 molar ratiobegan to be increased, with H2/C2 reaching 0.0090 by TIME 2 (in Table 2,day 2, 1835 hours). This increase caused a disturbance in the stableperformance of the reactor, as can be seen from both the upper plotgroup (LI Target (comparative example 4); LI_(P) example 3; and LITarget, example 3 with FI_(H) impact) and lower plot group (FI and FITarget) in FIG. 3. By using the improved algorithm to determine LeadingIndicator setpoint, in this case LI Target example 3 with FI_(H) impact,the reactor would have stabilized faster. The improved algorithmpredicts that LI setpoint should be decreased. Comparing LI requirementsbefore and after the change, we see that the improved algorithm wascorrect; the LI target at the start of the time span shown in FIG. 3 ishigher than the LI target at the end of this time span.

COMPARATIVE EXAMPLE 4 Control Action with No Leading Indicator SetpointAdjustment Using FI_(H)

The reactor was stable with H2/C2 at the same molar ratio and times ofexample 3. At TIME 1, as discussed in the above example 3, H2/C2 molarratio began to be increased, with H2/C2 reaching the level by TIME 2also as discussed in example 3. This increase caused a disturbance inthe stable performance of the reactor. Product FI, measured in thelaboratory, decreased to below target values then increased to abovetarget values before stabilizing (as seen in FIG. 3 for FI). These FIchanges were significant enough to affect product performance and causeout of specification product that is of substantially lower value thanprime specification product. The leading indicator setpoint in thisexample (shown as LI Target (comparative example 4) in the Figure) wasnot adjusted until about 10 hours after TIME 1. This leading indicatoris shown in FIG. 3 as “LI Target comparative example 4”. This lateadjustment exacerbated the fluctuations in FI.

EXAMPLE 5 Impact of changes in FI_(H) on Leading Indicator Setpoint

The following example shows the dramatic effect that changes in FI_(H)have on the Leading Indicator setpoint. If FI_(H) changes are notaccounted for, the reactor produces lower-value polymer.

This example shows data from the same reaction system and catalyst asused in Example 3. The data shown in Table 3 represent averageconditions over a period of several hours. FIG. 4 shows the Table 3 datain graphical form. Table 3 and FIG. 4 clearly show that as FI_(H)increases, the LI must be lower to produce granule I_(21.6) near thetarget of 10. The LI in this example is based on hexene-1 to ethylenefeed and gas ratios. TABLE 3 Impact of FI H on Leading Indicator TimeKEY REACTOR Day 1 Day 2 Day 3 Day 3 Day 4 Day 5 Day 5 Day 6 PARAMETERSUNITS 22:00 8:00 5:00 20:00 6:00 7:30 22:00 10:00 Production Rate Ton/hr12.27 11.39 10.30 33.21 34.46 36.15 36.76 35.31 Ethylene partial bara11.18 11.12 11.01 14.15 14.08 14.08 13.98 13.96 pressure H2/C2 molarratio mol/ 0.0111 0.0111 0.0110 0.0111 0.0090 0.0070 0.0070 0.0070 incycle gas mol Co-catalyst wt ppm 101 110 123 115 115 115 116 120feedrate Granule I21.6 (FI) dg/min 9.68 13.46 10.50 9.91 8.90 8.74 8.688.73 Granule I2.16 dg/min 0.07 0.09 0.09 0.11 0.10 0.08 0.08 0.08 FI H,calculated dg/min 0.315 0.304 0.427 0.604 0.562 0.451 0.458 0.448 C6LEAD INDICATOR 2.28 2.20 2.06 1.57 1.56 1.66 1.60 1.60

While the present invention has been described and illustrated byreference to some embodiments, those of ordinary skill in the art willappreciate that the invention lends itself to many different variationsnot illustrated herein. For these reasons, then, reference should bemade solely to the appended claims for purposes of determining the scopeof the present invention. Further, certain features of the presentinvention are described in terms of a set of numerical upper limits anda set of numerical lower limits. It should be appreciated that rangesformed by any combination of these limits are within the scope of theinvention unless otherwise indicated.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties, reaction conditions, and so forth, used in thespecification and claims are to be understood as approximations based onthe desired properties sought to be obtained by the present invention,and the error of measurement, and should at least be construed in lightof the number of reported significant digits and by applying ordinaryrounding techniques. Notwithstanding that the numerical ranges andvalues setting forth the broad scope of the invention areapproximations, the numerical values set forth are reported as preciselyas possible.

All priority documents are herein fully incorporated by reference forall jurisdictions in which such incorporation is permitted. Further, alldocuments cited herein, including testing procedures, are herein fullyincorporated by reference for all jurisdictions in which suchincorporation is permitted.

Various tradenames used herein are indicated by a ™ symbol, indicatingthat the names may be protected by certain trademark rights. Some suchnames may also be registered trademarks in various jurisdictions.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the invention asdefined by the appended claims. Moreover, the scope of the presentapplication is not intended to be limited to the particular embodimentsof the process, machine, manufacture, composition of matter, means,methods and steps described in the specification. As one will readilyappreciate from the disclosure, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized. Accordingly, the appended claims areintended to include within their scope such processes, machines,manufacture, compositions of matter, means, methods, or steps.

1. A method of olefin polymerization, the method comprising: (a)determining a flow ratio to a polymerization reactor, FR₁, of acomonomer or hydrogen flow rate to a monomer flow rate provided to thereactor; determining the concentration ratio, GR₁, of the concentrationof the selected comonomer or hydrogen to the concentration of themonomer in a recycle stream of the reactor, (b) obtaining a leadingindicator function, LI, defined by: $\begin{matrix}{{LI} = {\frac{{FR}_{1}}{{GR}_{1}} = \frac{{(\beta)\left( {FR}_{2} \right)} + {\left( {1 - \beta} \right)\left( {FR}_{3} \right)}}{{GR}_{1}}}} & \left( {1a} \right)\end{matrix}$ where GR₁ is the present value of either of thecomonomer/ethylene concentration ratio or the present value of thehydrogen/ethylene concentration ratio at time T in the reactor, asdetermined by analysis of the recycle stream; where FR₁ is the presentvalue of the flow ratio into the reactor of either of thecomonomer/ethylene ratio or the present value of the hydrogen/ethyleneratio, expressed as an exponentially weighted moving average (EWMA) attime T; where FR₂ is the instantaneous flow ratio td minutes prior totime T; where FR₃ is an EWMA using the comonomer or hydrogen residencetime td minutes prior to time T−1; where β=1−exp(−T/(comonomer residencetime)=1−exp(Δt/τ); where Δt=the time step chosen to update the LIcalculation; where τ=the residence time in the reactor of the one ofcomonomer or hydrogen that is used to calculate the LI with the provisothat the comonomer dissolved in the polymerized olefin is included insaid comonomer used to calculate the LI; (c) comparing the LI to atarget value; and (d) adjusting at least one reactor parameter inresponse to a deviation between the LI and the target value.
 2. Themethod of claim 1, wherein the olefin polymerization takes place in areactor selected from the group consisting of a solution reactor, aslurry loop reactor, a supercritical loop reactor, or a fluidized-bed,gas-phase reactor.
 3. The method of claim 1, wherein the olefinpolymerization takes place in a gas-phase fluidized bed reactor.
 4. Themethod of claim 1, wherein the monomer is ethylene and the comonomer isselected from the group consisting of C₃-C₁₂ alpha-olefins and mixturesthereof.
 5. The method of claim 1, wherein the monomer is ethylene andthe comonomer is selected from the group consisting of C₃-C₈alpha-olefins and mixtures thereof.
 6. The method of claim 1, whereinthe monomer is ethylene and the comonomer is selected from the groupconsisting of C₃-C₆ alpha-olefins and mixtures thereof.
 7. The method ofclaim 1, wherein the at least one reactor parameter is selected from thegroup consisting of monomer feed rate, comonomer feed rates, catalystfeed rates, cocatalyst feed rates, hydrogen feed rate, reactortemperature, monomer partial pressure, comonomer partial pressure,hydrogen partial pressure, water feed rate, carbon dioxide feed rate,impurity feedrate, condensing agent feedrate, isopropyl alcoholfeedrate, oxygen feedrate, and combinations thereof.
 8. The method ofclaim 1, wherein the olefin polymerization is catalyzed by a catalystsystem comprising at least one first catalyst and at least one secondcatalyst, wherein the method produces a polymer product comprising amolecular weight distribution or a composition distribution, or both,that are broad or bimodal, or both.
 9. The method of claim 8, whereinthe adjusting of said at least one reactor parameter is effective toalter the relative productivity of the at least one said first or the atleast one said second catalysts.
 10. The method of claim 8, wherein thecatalyst system comprises at least one metallocene catalyst and at leastone non-metallocene catalyst.
 11. The method of claim 10, wherein the atleast one metallocene and the at least one non-metallocene catalysts aresupported and are both present on the same support.
 12. The method ofclaim 1, further comprising producing a polymer product, wherein theolefin polymerization is catalyzed by a supported bimetallic catalystsystem comprising at least one metallocene catalyst and at least onenon-metallocene transition metal catalyst, and wherein said polymerproduct comprises a molecular weight distribution, a compositiondistribution, or both a molecular weight distribution and a compositiondistribution, that are broad or bimodal, or both broad and bimodal. 13.The method of claims 10, 11, or 12 wherein the at least one metallocenecatalyst compound is (RCp)₂MX₂, wherein Cp is a substitutedcyclopentadienyl ring, M is a Group 4 metal; R is an alkyl, and X is ahalide.
 14. The method of claim 13, wherein M is zirconium; R isn-butyl, and X is fluoride.
 15. A method to achieve control of a leadingindicator in a gas phase polymerization reaction in a polymerizationreactor, comprising: a) calculating a leading indicator, (LI), said LIcomprising a numerator and a denominator, such that the numerator andthe denominator have the same dynamic response to process changes; b)choosing at least one process sensitive variable to manipulate tocontrol said leading indicator (LI); c) manipulating the processsensitive variable; and d) removing a polymer product.
 16. The method ofclaim 15 wherein the at least one process sensitive variable is waterfeedrate.
 17. The method of claim 15, wherein said polymerizationcomprises ethylene, a comonomer selected from 1-butene, 1-hexene,1-octene or combinations thereof, and hydrogen.
 18. The method of claim15 wherein control of the leading indicator function is achieved bymanual, automatic, or a combination of manual and automatic adjustmentsof reactor conditions.
 19. The method of claim 15, wherein said leadingindicator, LI is determined by: where $\begin{matrix}{{LI} = {\frac{{FR}_{1}}{{GR}_{1}} = \frac{{(\beta)\left( {FR}_{2} \right)} + {\left( {1 - \beta} \right)\left( {FR}_{3} \right)}}{{GR}_{1}}}} & \left( {1a} \right)\end{matrix}$ GR₁=present value of either of the comonomer/ethyleneconcentration ratio or the present value of the hydrogen/ethyleneconcentration ratio at time T in the reactor, as determined by analysisof a recycle stream of said reactor; where FR₁ is the present value ofthe flow ratio of either of the comonomer/ethylene ratio or the presentvalue of the hydrogen/ethylene ratio into the reactor expressed as anexponentially weighted moving average (EWMA) at time T; where FR₂ is theinstantaneous Flow Ratio td minutes prior to time step T; where FR₃ isan EWMA using the comonomer or hydrogen residence time td minutes priorto time step T−1; where β=1−exp(−T/(comonomer residencetime)=1−exp(Δt/τ); where τt=the time step chosen to update the LIcalculation; where τ=the residence time of the one of comonomer orhydrogen that is used to calculate the LI, with the proviso that thecomonomer dissolved in the polymer product is included in said comonomerused to calculate the LI; said method further comprising (c) comparingLI to a target value; and (d) adjusting at least one reactor parameterin response to a deviation in LI and the target value.
 20. The method ofclaim 19, wherein said polymerization reaction further comprises acatalyst system comprising at least one first catalyst and at least onesecond catalyst, wherein the polymer product comprises a molecularweight distribution or a composition distribution, or both, that arebroad or bimodal, or both.
 21. The method of claim 20, wherein thecatalyst system comprises at least one metallocene catalyst and at leastone non-metallocene catalyst.
 22. The method of claim 21, wherein the atleast one metallocene and the at least one non-metallocene catalysts aresupported and are both present on the same support.
 23. The method ofclaim 19, wherein the olefin polymerization is catalyzed by a supportedbimetallic catalyst system comprising at least one metallocene catalystand at least one non-metallocene transition metal catalyst, and whereinsaid polymer product comprises a molecular weight distribution, acomposition distribution, or both a molecular weight distribution and acomposition distribution, that are broad or bimodal, or both broad andbimodal.
 24. The method of claim 23 wherein the at least one metallocenecatalyst compound is (RCp)₂MX₂, wherein Cp is a substitutedcyclopentadienyl ring, M is a Group 4 metal; R is an alkyl, and X is ahalide.
 25. The method of claim 24 wherein M is zirconium; R is n-butyl,and X is fluoride.
 26. A process for polymerizing olefins in a gas-phasefluidized bed polymerization reactor, the process comprising: (a)determining a flow ratio into the polymerization reactor, FR₁, of acomonomer or hydrogen flow rate to a monomer flow rate provided to thereactor; determining the concentration ratio, GR₁, of the selectedcomonomer or hydrogen concentration to the monomer concentration in arecycle gas stream of the reactor, (b) obtaining a leading indicatorfunction, LI, defined by: $\begin{matrix}{{LI} = {\frac{{FR}_{1}}{{GR}_{1}} = \frac{{(\beta)\left( {FR}_{2} \right)} + {\left( {1 - \beta} \right)\left( {FR}_{3} \right)}}{{GR}_{1}}}} & \left( {1a} \right)\end{matrix}$ where GR₁ is the present value of either of thecomonomer/ethylene concentration ratio or the present value of thehydrogen/ethylene concentration ratio at time T in the reactor, asdetermined by analysis of the recycle gas stream; where FR₁ is thepresent value of the flow ratio into the reactor of either of thecomonomer/ethylene ratio or the present value of the hydrogen/ethyleneratio, expressed as an exponentially weighted moving average (EWMA) attime T; where FR₂ is the instantaneous flow ratio td minutes prior totime T; where FR₃ is an EWMA using the comonomer or hydrogen residencetime td minutes prior to time T−1; where β=1−exp(−T/(comonomer residencetime)=1−exp(Δt/τ); where Δt=the time step chosen to update the LIcalculation; where τ=the residence time in the reactor of the one ofcomonomer or hydrogen that is used to calculate the LI, with the provisothat the comonomer dissolved in a polymer made in the olefinpolymerization, is included in said comonomer used to calculate the LI;(c) comparing the LI to a target value; and (d) adjusting at least onereactor parameter in response to a deviation between the LI and thetarget value; wherein said polymerization comprises said ethylene, saidcomonomer selected from 1-butene, 1-hexene or combinations thereof, andhydrogen; wherein the olefin polymerization is catalyzed by a supportedbimetallic catalyst system comprising at least one metallocene catalystand at least one non-metallocene transition metal catalyst, and whereinsaid polymer product comprises a molecular weight distribution, acomposition distribution, or both a molecular weight distribution and acomposition distribution, that are broad or bimodal, or both broad andbimodal; wherein the at least one metallocene catalyst compound is(RCp)₂MX₂, wherein Cp is a substituted cyclopentadienyl ring, M iszirconium; R is a n-butyl, and X is fluoride; wherein the at least onereactor parameter is selected from the group consisting of monomer feedrate, comonomer feed rates, catalyst feed rates, cocatalyst feed rates,hydrogen feed rate, reactor temperature, monomer partial pressure,comonomer partial pressure, hydrogen partial pressure, water feed rate,carbon dioxide feed rate, impurity feedrate, condensing agent feedrate,isopropyl alcohol feedrate, oxygen feedrate, and combinations thereof.